chore: Release

fix typo

.github/workflows/rust.yml

@@ -23,7 +23,7 @@ jobs:
         with:
           globs: "exercises/**/*.md"
       - name: Run cargo fmt
-        run: cargo fmt --all -- --check
+        run: cargo fmt --all --check
   test:
     runs-on: ${{ matrix.os }}
     strategy:
@@ -33,7 +33,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: swatinem/rust-cache@v2
       - name: Run cargo test
-        run: cargo test
+        run: cargo test --workspace
   dev-check:
     runs-on: ubuntu-latest
     steps:

.typos.toml

@@ -2,6 +2,3 @@
 extend-exclude = [
   "CHANGELOG.md",
 ]
-
-[default.extend-words]
-"ratatui" = "ratatui"

CHANGELOG.md

@@ -1,3 +1,62 @@
+<a name="6.3.0"></a>
+
+## 6.3.0 (2024-08-29)
+
+### Added
+
+- Add the following exercise lints:
+  - `forbid(unsafe_code)`: You shouldn't write unsafe code in Rustlings.
+  - `forbid(unstable_features)`: You don't need unstable features in Rustlings and shouldn't rely on them while learning Rust.
+  - `forbid(todo)`: You forgot a `todo!()`.
+  - `forbid(empty_loop)`: This can only happen by mistake in Rustlings.
+  - `deny(infinite_loop)`: No infinite loops are needed in Rustlings.
+  - `deny(mem_forget)`: You shouldn't leak memory while still learning Rust.
+- Show a link to every exercise file in the list.
+- Add scroll padding in the list.
+- Break the help footer of the list into two lines when the terminal width isn't big enough.
+- Enable scrolling with the mouse in the list.
+- `dev check`: Show the progress of checks.
+- `dev check`: Check that the length of all exercise names is lower than 32.
+- `dev check`: Check if exercise contains no tests and isn't marked with `test = false`.
+
+### Changed
+
+- The compilation time when installing Rustlings is reduced.
+- Pressing `c` in the list for "continue on" now quits the list after setting the selected exercise as the current one.
+- Better highlighting of the solution file after an exercise is done.
+- Don't show the output of successful tests anymore. Instead, show the pretty output for tests.
+- Be explicit about `q` only quitting the list and not the whole program in the list.
+- Be explicit about `r` only resetting one exercise (the selected one) in the list.
+- Ignore the standard output of `git init`.
+- `threads3`: Remove the queue length and improve tests.
+- `errors4`: Use match instead of a comparison chain in the solution.
+- `functions3`: Only take `u8` to avoid using a too high number of iterations by mistake.
+- `dev check`: Always check with strict Clippy (warnings to errors) when checking the solutions.
+
+### Fixed
+
+- Fix the error on some systems about too many open files during the final check of all exercises.
+- Fix the list when the terminal height is too low.
+- Restore the terminal after an error in the list.
+
+<a name="6.2.0"></a>
+
+## 6.2.0 (2024-08-09)
+
+### Added
+
+- Show a message before checking and running an exercise. This gives the user instant feedback and avoids confusion if the checks take too long.
+- Show a helpful error message when trying to install Rustlings with a Rust version lower than the minimum one that Rustlings supports.
+- Add a `README.md` file to the `solutions/` directory.
+- Allow initializing Rustlings in a Cargo workspace.
+- `dev check`: Check that all solutions are formatted with `rustfmt`.
+
+### Changed
+
+- Remove the state file and the solutions directory from the generated `.gitignore` file.
+- Run the final check of all exercises in parallel.
+- Small exercise improvements.
+
 <a name="6.1.0"></a>
 
 ## 6.1.0 (2024-07-10)

Cargo.lock

@@ -14,26 +14,11 @@ dependencies = [
  "zerocopy",
 ]
 
-[[package]]
-name = "aho-corasick"
-version = "1.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
-dependencies = [
- "memchr",
-]
-
-[[package]]
-name = "allocator-api2"
-version = "0.2.18"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c6cb57a04249c6480766f7f7cef5467412af1490f8d1e243141daddada3264f"
-
 [[package]]
 name = "anstream"
-version = "0.6.14"
+version = "0.6.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "418c75fa768af9c03be99d17643f93f79bbba589895012a80e3452a19ddda15b"
+checksum = "64e15c1ab1f89faffbf04a634d5e1962e9074f2741eef6d97f3c4e322426d526"
 dependencies = [
  "anstyle",
  "anstyle-parse",
@@ -46,33 +31,33 @@ dependencies = [
 
 [[package]]
 name = "anstyle"
-version = "1.0.7"
+version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "038dfcf04a5feb68e9c60b21c9625a54c2c0616e79b72b0fd87075a056ae1d1b"
+checksum = "1bec1de6f59aedf83baf9ff929c98f2ad654b97c9510f4e70cf6f661d49fd5b1"
 
 [[package]]
 name = "anstyle-parse"
-version = "0.2.4"
+version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c03a11a9034d92058ceb6ee011ce58af4a9bf61491aa7e1e59ecd24bd40d22d4"
+checksum = "eb47de1e80c2b463c735db5b217a0ddc39d612e7ac9e2e96a5aed1f57616c1cb"
 dependencies = [
  "utf8parse",
 ]
 
 [[package]]
 name = "anstyle-query"
-version = "1.1.0"
+version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ad186efb764318d35165f1758e7dcef3b10628e26d41a44bc5550652e6804391"
+checksum = "6d36fc52c7f6c869915e99412912f22093507da8d9e942ceaf66fe4b7c14422a"
 dependencies = [
  "windows-sys 0.52.0",
 ]
 
 [[package]]
 name = "anstyle-wincon"
-version = "3.0.3"
+version = "3.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61a38449feb7068f52bb06c12759005cf459ee52bb4adc1d5a7c4322d716fb19"
+checksum = "5bf74e1b6e971609db8ca7a9ce79fd5768ab6ae46441c572e46cf596f59e57f8"
 dependencies = [
  "anstyle",
  "windows-sys 0.52.0",
@@ -84,21 +69,6 @@ version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b3d1d046238990b9cf5bcde22a3fb3584ee5cf65fb2765f454ed428c7a0063da"
 
-[[package]]
-name = "assert_cmd"
-version = "2.0.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed72493ac66d5804837f480ab3766c72bdfab91a65e565fc54fa9e42db0073a8"
-dependencies = [
- "anstyle",
- "bstr",
- "doc-comment",
- "predicates",
- "predicates-core",
- "predicates-tree",
- "wait-timeout",
-]
-
 [[package]]
 name = "autocfg"
 version = "1.3.0"
@@ -117,32 +87,6 @@ version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
 
-[[package]]
-name = "bstr"
-version = "1.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05efc5cfd9110c8416e471df0e96702d58690178e206e61b7173706673c93706"
-dependencies = [
- "memchr",
- "regex-automata",
- "serde",
-]
-
-[[package]]
-name = "cassowary"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df8670b8c7b9dae1793364eafadf7239c40d669904660c5960d74cfd80b46a53"
-
-[[package]]
-name = "castaway"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0abae9be0aaf9ea96a3b1b8b1b55c602ca751eba1b1500220cea4ecbafe7c0d5"
-dependencies = [
- "rustversion",
-]
-
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -151,9 +95,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clap"
-version = "4.5.9"
+version = "4.5.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "64acc1846d54c1fe936a78dc189c34e28d3f5afc348403f28ecf53660b9b8462"
+checksum = "ed6719fffa43d0d87e5fd8caeab59be1554fb028cd30edc88fc4369b17971019"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -161,9 +105,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.9"
+version = "4.5.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6fb8393d67ba2e7bfaf28a23458e4e2b543cc73a99595511eb207fdb8aede942"
+checksum = "216aec2b177652e3846684cbfe25c9964d18ec45234f0f5da5157b207ed1aab6"
 dependencies = [
  "anstream",
  "anstyle",
@@ -173,9 +117,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.5.8"
+version = "4.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2bac35c6dafb060fd4d275d9a4ffae97917c13a6327903a8be2153cd964f7085"
+checksum = "501d359d5f3dcaf6ecdeee48833ae73ec6e42723a1e52419c79abf9507eec0a0"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -185,28 +129,15 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.7.1"
+version = "0.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4b82cf0babdbd58558212896d1a4272303a57bdb245c2bf1147185fb45640e70"
+checksum = "1462739cb27611015575c0c11df5df7601141071f07518d56fcc1be504cbec97"
 
 [[package]]
 name = "colorchoice"
-version = "1.0.1"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b6a852b24ab71dffc585bcb46eaf7959d175cb865a7152e35b348d1b2960422"
-
-[[package]]
-name = "compact_str"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f86b9c4c00838774a6d902ef931eff7470720c51d90c2e32cfe15dc304737b3f"
-dependencies = [
- "castaway",
- "cfg-if",
- "itoa",
- "ryu",
- "static_assertions",
-]
+checksum = "d3fd119d74b830634cea2a0f58bbd0d54540518a14397557951e79340abc28c0"
 
 [[package]]
 name = "crossbeam-channel"
@@ -225,15 +156,15 @@ checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
 
 [[package]]
 name = "crossterm"
-version = "0.27.0"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f476fe445d41c9e991fd07515a6f463074b782242ccf4a5b7b1d1012e70824df"
+checksum = "829d955a0bb380ef178a640b91779e3987da38c9aea133b20614cfed8cdea9c6"
 dependencies = [
  "bitflags 2.6.0",
  "crossterm_winapi",
- "libc",
- "mio",
+ "mio 1.0.2",
  "parking_lot",
+ "rustix",
  "signal-hook",
  "signal-hook-mio",
  "winapi",
@@ -248,24 +179,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "difflib"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
-
-[[package]]
-name = "doc-comment"
-version = "0.3.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
-
-[[package]]
-name = "either"
-version = "1.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
-
 [[package]]
 name = "equivalent"
 version = "1.0.1"
@@ -273,24 +186,31 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
 [[package]]
-name = "filetime"
-version = "0.2.23"
+name = "errno"
+version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ee447700ac8aa0b2f2bd7bc4462ad686ba06baa6727ac149a2d6277f0d240fd"
+checksum = "534c5cf6194dfab3db3242765c03bbe257cf92f22b38f6bc0c58d59108a820ba"
 dependencies = [
- "cfg-if",
  "libc",
- "redox_syscall 0.4.1",
  "windows-sys 0.52.0",
 ]
 
 [[package]]
-name = "float-cmp"
-version = "0.9.0"
+name = "fastrand"
+version = "2.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "98de4bbd547a563b716d8dfa9aad1cb19bfab00f4fa09a6a4ed21dbcf44ce9c4"
+checksum = "e8c02a5121d4ea3eb16a80748c74f5549a5665e4c21333c6098f283870fbdea6"
+
+[[package]]
+name = "filetime"
+version = "0.2.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35c0522e981e68cbfa8c3f978441a5f34b30b96e146b33cd3359176b50fe8586"
 dependencies = [
- "num-traits",
+ "cfg-if",
+ "libc",
+ "libredox",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -307,10 +227,6 @@ name = "hashbrown"
 version = "0.14.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
-dependencies = [
- "ahash",
- "allocator-api2",
-]
 
 [[package]]
 name = "heck"
@@ -319,10 +235,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
 
 [[package]]
-name = "indexmap"
-version = "2.2.6"
+name = "hermit-abi"
+version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
+
+[[package]]
+name = "indexmap"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93ead53efc7ea8ed3cfb0c79fc8023fbb782a5432b52830b6518941cebe6505c"
 dependencies = [
  "equivalent",
  "hashbrown",
@@ -350,18 +272,9 @@ dependencies = [
 
 [[package]]
 name = "is_terminal_polyfill"
-version = "1.70.0"
+version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f8478577c03552c21db0e2724ffb8986a5ce7af88107e6be5d2ee6e158c12800"
-
-[[package]]
-name = "itertools"
-version = "0.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
-dependencies = [
- "either",
-]
+checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
 [[package]]
 name = "itoa"
@@ -391,9 +304,26 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.155"
+version = "0.2.158"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+checksum = "d8adc4bb1803a324070e64a98ae98f38934d91957a99cfb3a43dcbc01bc56439"
+
+[[package]]
+name = "libredox"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0ff37bd590ca25063e35af745c343cb7a0271906fb7b37e4813e8f79f00268d"
+dependencies = [
+ "bitflags 2.6.0",
+ "libc",
+ "redox_syscall",
+]
+
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78b3ae25bc7c8c38cec158d1f2757ee79e9b3740fbc7ccf0e59e4b08d793fa89"
 
 [[package]]
 name = "lock_api"
@@ -411,15 +341,6 @@ version = "0.4.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
 
-[[package]]
-name = "lru"
-version = "0.12.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3262e75e648fce39813cb56ac41f3c3e3f65217ebf3844d818d1f9398cfb0dc"
-dependencies = [
- "hashbrown",
-]
-
 [[package]]
 name = "memchr"
 version = "2.7.4"
@@ -439,10 +360,17 @@ dependencies = [
 ]
 
 [[package]]
-name = "normalize-line-endings"
-version = "0.3.0"
+name = "mio"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61807f77802ff30975e01f4f071c8ba10c022052f98b3294119f3e615d13e5be"
+checksum = "80e04d1dcff3aae0704555fe5fee3bcfaf3d1fdf8a7e521d5b9d2b42acb52cec"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "log",
+ "wasi",
+ "windows-sys 0.52.0",
+]
 
 [[package]]
 name = "notify"
@@ -458,7 +386,7 @@ dependencies = [
  "kqueue",
  "libc",
  "log",
- "mio",
+ "mio 0.8.11",
  "walkdir",
  "windows-sys 0.48.0",
 ]
@@ -473,15 +401,6 @@ dependencies = [
  "notify",
 ]
 
-[[package]]
-name = "num-traits"
-version = "0.2.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "once_cell"
 version = "1.19.0"
@@ -490,12 +409,12 @@ checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
 [[package]]
 name = "os_pipe"
-version = "1.2.0"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "29d73ba8daf8fac13b0501d1abeddcfe21ba7401ada61a819144b6c2a4f32209"
+checksum = "5ffd2b0a5634335b135d5728d84c5e0fd726954b87111f7506a61c502280d982"
 dependencies = [
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -516,47 +435,11 @@ checksum = "1e401f977ab385c9e4e3ab30627d6f26d00e2c73eef317493c4ec6d468726cf8"
 dependencies = [
  "cfg-if",
  "libc",
- "redox_syscall 0.5.2",
+ "redox_syscall",
  "smallvec",
  "windows-targets 0.52.6",
 ]
 
-[[package]]
-name = "paste"
-version = "1.0.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57c0d7b74b563b49d38dae00a0c37d4d6de9b432382b2892f0574ddcae73fd0a"
-
-[[package]]
-name = "predicates"
-version = "3.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68b87bfd4605926cdfefc1c3b5f8fe560e3feca9d5552cf68c466d3d8236c7e8"
-dependencies = [
- "anstyle",
- "difflib",
- "float-cmp",
- "normalize-line-endings",
- "predicates-core",
- "regex",
-]
-
-[[package]]
-name = "predicates-core"
-version = "1.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b794032607612e7abeb4db69adb4e33590fa6cf1149e95fd7cb00e634b92f174"
-
-[[package]]
-name = "predicates-tree"
-version = "1.0.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "368ba315fb8c5052ab692e68a0eefec6ec57b23a36959c14496f0b0df2c0cecf"
-dependencies = [
- "predicates-core",
- "termtree",
-]
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.86"
@@ -568,115 +451,61 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.36"
+version = "1.0.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
 dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "ratatui"
-version = "0.27.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d16546c5b5962abf8ce6e2881e722b4e0ae3b6f1a08a26ae3573c55853ca68d3"
-dependencies = [
- "bitflags 2.6.0",
- "cassowary",
- "compact_str",
- "crossterm",
- "itertools",
- "lru",
- "paste",
- "stability",
- "strum",
- "strum_macros",
- "unicode-segmentation",
- "unicode-truncate",
- "unicode-width",
-]
-
 [[package]]
 name = "redox_syscall"
-version = "0.4.1"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4722d768eff46b75989dd134e5c353f0d6296e5aaa3132e776cbdb56be7731aa"
-dependencies = [
- "bitflags 1.3.2",
-]
-
-[[package]]
-name = "redox_syscall"
-version = "0.5.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c82cf8cff14456045f55ec4241383baeff27af886adb72ffb2162f99911de0fd"
+checksum = "2a908a6e00f1fdd0dfd9c0eb08ce85126f6d8bbda50017e74bc4a4b7d4a926a4"
 dependencies = [
  "bitflags 2.6.0",
 ]
 
 [[package]]
-name = "regex"
-version = "1.10.5"
+name = "rustix"
+version = "0.38.35"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b91213439dad192326a0d7c6ee3955910425f441d7038e0d6933b0aec5c4517f"
+checksum = "a85d50532239da68e9addb745ba38ff4612a242c1c7ceea689c4bc7c2f43c36f"
 dependencies = [
- "aho-corasick",
- "memchr",
- "regex-automata",
- "regex-syntax",
+ "bitflags 2.6.0",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.52.0",
 ]
 
-[[package]]
-name = "regex-automata"
-version = "0.4.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "38caf58cc5ef2fed281f89292ef23f6365465ed9a41b7a7754eb4e26496c92df"
-dependencies = [
- "aho-corasick",
- "memchr",
- "regex-syntax",
-]
-
-[[package]]
-name = "regex-syntax"
-version = "0.8.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a66a03ae7c801facd77a29370b4faec201768915ac14a721ba36f20bc9c209b"
-
 [[package]]
 name = "rustlings"
-version = "6.1.0"
+version = "6.3.0"
 dependencies = [
+ "ahash",
  "anyhow",
- "assert_cmd",
  "clap",
  "crossterm",
- "hashbrown",
  "notify-debouncer-mini",
  "os_pipe",
- "predicates",
- "ratatui",
  "rustlings-macros",
  "serde",
  "serde_json",
+ "tempfile",
  "toml_edit",
 ]
 
 [[package]]
 name = "rustlings-macros"
-version = "6.1.0"
+version = "6.3.0"
 dependencies = [
  "quote",
  "serde",
  "toml_edit",
 ]
 
-[[package]]
-name = "rustversion"
-version = "1.0.17"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "955d28af4278de8121b7ebeb796b6a45735dc01436d898801014aced2773a3d6"
-
 [[package]]
 name = "ryu"
 version = "1.0.18"
@@ -700,18 +529,18 @@ checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
 name = "serde"
-version = "1.0.204"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bc76f558e0cbb2a839d37354c575f1dc3fdc6546b5be373ba43d95f231bf7c12"
+checksum = "99fce0ffe7310761ca6bf9faf5115afbc19688edd00171d81b1bb1b116c63e09"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.204"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e0cd7e117be63d3c3678776753929474f3b04a43a080c744d6b0ae2a8c28e222"
+checksum = "a5831b979fd7b5439637af1752d535ff49f4860c0f341d1baeb6faf0f4242170"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -720,20 +549,21 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.120"
+version = "1.0.127"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e0d21c9a8cae1235ad58a00c11cb40d4b1e5c784f1ef2c537876ed6ffd8b7c5"
+checksum = "8043c06d9f82bd7271361ed64f415fe5e12a77fdb52e573e7f06a516dea329ad"
 dependencies = [
  "itoa",
+ "memchr",
  "ryu",
  "serde",
 ]
 
 [[package]]
 name = "serde_spanned"
-version = "0.6.6"
+version = "0.6.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "79e674e01f999af37c49f70a6ede167a8a60b2503e56c5599532a65baa5969a0"
+checksum = "eb5b1b31579f3811bf615c144393417496f152e12ac8b7663bf664f4a815306d"
 dependencies = [
  "serde",
 ]
@@ -750,12 +580,12 @@ dependencies = [
 
 [[package]]
 name = "signal-hook-mio"
-version = "0.2.3"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "29ad2e15f37ec9a6cc544097b78a1ec90001e9f71b81338ca39f430adaca99af"
+checksum = "34db1a06d485c9142248b7a054f034b349b212551f3dfd19c94d45a754a217cd"
 dependencies = [
  "libc",
- "mio",
+ "mio 1.0.2",
  "signal-hook",
 ]
 
@@ -774,55 +604,17 @@ version = "1.13.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
 
-[[package]]
-name = "stability"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d904e7009df136af5297832a3ace3370cd14ff1546a232f4f185036c2736fcac"
-dependencies = [
- "quote",
- "syn",
-]
-
-[[package]]
-name = "static_assertions"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
-
 [[package]]
 name = "strsim"
 version = "0.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
-[[package]]
-name = "strum"
-version = "0.26.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fec0f0aef304996cf250b31b5a10dee7980c85da9d759361292b8bca5a18f06"
-dependencies = [
- "strum_macros",
-]
-
-[[package]]
-name = "strum_macros"
-version = "0.26.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c6bee85a5a24955dc440386795aa378cd9cf82acd5f764469152d2270e581be"
-dependencies = [
- "heck",
- "proc-macro2",
- "quote",
- "rustversion",
- "syn",
-]
-
 [[package]]
 name = "syn"
-version = "2.0.70"
+version = "2.0.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f0209b68b3613b093e0ec905354eccaedcfe83b8cb37cbdeae64026c3064c16"
+checksum = "578e081a14e0cefc3279b0472138c513f37b41a08d5a3cca9b6e4e8ceb6cd525"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -830,25 +622,32 @@ dependencies = [
 ]
 
 [[package]]
-name = "termtree"
-version = "0.4.1"
+name = "tempfile"
+version = "3.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3369f5ac52d5eb6ab48c6b4ffdc8efbcad6b89c765749064ba298f2c68a16a76"
+checksum = "04cbcdd0c794ebb0d4cf35e88edd2f7d2c4c3e9a5a6dab322839b321c6a87a64"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.59.0",
+]
 
 [[package]]
 name = "toml_datetime"
-version = "0.6.6"
+version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4badfd56924ae69bcc9039335b2e017639ce3f9b001c393c1b2d1ef846ce2cbf"
+checksum = "0dd7358ecb8fc2f8d014bf86f6f638ce72ba252a2c3a2572f2a795f1d23efb41"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "toml_edit"
-version = "0.22.15"
+version = "0.22.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d59a3a72298453f564e2b111fa896f8d07fabb36f51f06d7e875fc5e0b5a3ef1"
+checksum = "583c44c02ad26b0c3f3066fe629275e50627026c51ac2e595cca4c230ce1ce1d"
 dependencies = [
  "indexmap",
  "serde",
@@ -863,29 +662,6 @@ version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
 
-[[package]]
-name = "unicode-segmentation"
-version = "1.11.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d4c87d22b6e3f4a18d4d40ef354e97c90fcb14dd91d7dc0aa9d8a1172ebf7202"
-
-[[package]]
-name = "unicode-truncate"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b3644627a5af5fa321c95b9b235a72fd24cd29c648c2c379431e6628655627bf"
-dependencies = [
- "itertools",
- "unicode-segmentation",
- "unicode-width",
-]
-
-[[package]]
-name = "unicode-width"
-version = "0.1.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0336d538f7abc86d282a4189614dfaa90810dfc2c6f6427eaf88e16311dd225d"
-
 [[package]]
 name = "utf8parse"
 version = "0.2.2"
@@ -894,18 +670,9 @@ checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
 [[package]]
 name = "version_check"
-version = "0.9.4"
+version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
-[[package]]
-name = "wait-timeout"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
-dependencies = [
- "libc",
-]
+checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
 [[package]]
 name = "walkdir"
@@ -941,11 +708,11 @@ checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 
 [[package]]
 name = "winapi-util"
-version = "0.1.8"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4d4cc384e1e73b93bafa6fb4f1df8c41695c8a91cf9c4c64358067d15a7b6c6b"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -972,6 +739,15 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets 0.52.6",
+]
+
 [[package]]
 name = "windows-targets"
 version = "0.48.5"
@@ -1095,9 +871,9 @@ checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "winnow"
-version = "0.6.13"
+version = "0.6.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59b5e5f6c299a3c7890b876a2a587f3115162487e704907d9b6cd29473052ba1"
+checksum = "68a9bda4691f099d435ad181000724da8e5899daa10713c2d432552b9ccd3a6f"
 dependencies = [
  "memchr",
 ]

Cargo.toml

@@ -1,27 +1,26 @@
 [workspace]
 resolver = "2"
 exclude = [
-  "tests/fixture/failure",
-  "tests/fixture/state",
-  "tests/fixture/success",
+  "tests/test_exercises",
   "dev",
 ]
 
 [workspace.package]
-version = "6.1.0"
+version = "6.3.0"
 authors = [
-  "Liv <mokou@fastmail.com>",
-  "Mo Bitar <mo8it@proton.me>",
+  "Mo Bitar <mo8it@proton.me>", # https://github.com/mo8it
+  "Liv <mokou@fastmail.com>", # https://github.com/shadows-withal
   # Alumni
-  "Carol (Nichols || Goulding) <carol.nichols@gmail.com>",
+  "Carol (Nichols || Goulding) <carol.nichols@gmail.com>", # https://github.com/carols10cents
 ]
 repository = "https://github.com/rust-lang/rustlings"
 license = "MIT"
-edition = "2021"
+edition = "2021" # On Update: Update the edition of the `rustfmt` command that checks the solutions.
+rust-version = "1.80"
 
 [workspace.dependencies]
-serde = { version = "1.0.204", features = ["derive"] }
-toml_edit = { version = "0.22.15", default-features = false, features = ["parse", "serde"] }
+serde = { version = "1.0.209", features = ["derive"] }
+toml_edit = { version = "0.22.20", default-features = false, features = ["parse", "serde"] }
 
 [package]
 name = "rustlings"
@@ -31,6 +30,7 @@ authors.workspace = true
 repository.workspace = true
 license.workspace = true
 edition.workspace = true
+rust-version.workspace = true
 keywords = [
   "exercise",
   "learning",
@@ -46,21 +46,19 @@ include = [
 ]
 
 [dependencies]
+ahash = { version = "0.8.11", default-features = false }
 anyhow = "1.0.86"
-clap = { version = "4.5.9", features = ["derive"] }
-crossterm = "0.27.0"
-hashbrown = "0.14.5"
+clap = { version = "4.5.16", features = ["derive"] }
+crossterm = { version = "0.28.1", default-features = false, features = ["windows", "events"] }
 notify-debouncer-mini = { version = "0.4.1", default-features = false }
-os_pipe = "1.2.0"
-ratatui = { version = "0.27.0", default-features = false, features = ["crossterm"] }
-rustlings-macros = { path = "rustlings-macros", version = "=6.1.0" }
-serde_json = "1.0.120"
+os_pipe = "1.2.1"
+rustlings-macros = { path = "rustlings-macros", version = "=6.3.0" }
+serde_json = "1.0.127"
 serde.workspace = true
 toml_edit.workspace = true
 
 [dev-dependencies]
-assert_cmd = "2.0.14"
-predicates = "3.1.0"
+tempfile = "3.12.0"
 
 [profile.release]
 panic = "abort"
@@ -70,3 +68,21 @@ panic = "abort"
 
 [package.metadata.release]
 pre-release-hook = ["./release-hook.sh"]
+
+[workspace.lints.rust]
+unsafe_code = "forbid"
+unstable_features = "forbid"
+
+[workspace.lints.clippy]
+empty_loop = "forbid"
+disallowed-types = "deny"
+disallowed-methods = "deny"
+infinite_loop = "deny"
+mem_forget = "deny"
+dbg_macro = "warn"
+todo = "warn"
+# TODO: Remove after the following fix is released: https://github.com/rust-lang/rust-clippy/pull/13102
+needless_option_as_deref = "allow"
+
+[lints]
+workspace = true

README.md

@@ -17,7 +17,7 @@ It contains code examples and exercises similar to Rustlings, but online.
 
 ### Installing Rust
 
-Before installing Rustlings, you need to have _Rust installed_.
+Before installing Rustlings, you need to have the **latest version of Rust** installed.
 Visit [www.rust-lang.org/tools/install](https://www.rust-lang.org/tools/install) for further instructions on installing Rust.
 This will also install _Cargo_, Rust's package/project manager.
 
@@ -53,6 +53,21 @@ After installing Rustlings, run the following command to initialize the `rustlin
 rustlings init
 ```
 
+<details>
+<summary><strong>If the command <code>rustlings</code> can't be found…</strong> (<em>click to expand</em>)</summary>
+
+You are probably using Linux and installed Rust using your package manager.
+
+Cargo installs binaries to the directory `~/.cargo/bin`.
+Sadly, package managers often don't add `~/.cargo/bin` to your `PATH` environment variable.
+
+The solution is to …
+
+- either add `~/.cargo/bin` manually to `PATH`
+- or to uninstall Rust from the package manager and install it using the official way with `rustup`: https://www.rust-lang.org/tools/install
+
+</details>
+
 Now, go into the newly initialized directory and launch Rustlings for further instructions on getting started with the exercises:
 
 ```bash
@@ -73,8 +88,6 @@ While working with Rustlings, please use a modern terminal for the best user exp
 The default terminal on Linux and Mac should be sufficient.
 On Windows, we recommend the [Windows Terminal](https://aka.ms/terminal).
 
-If you use VS Code, the builtin terminal should also be fine.
-
 ## Doing exercises
 
 The exercises are sorted by topic and can be found in the subdirectory `exercises/<topic>`.

clippy.toml

@@ -0,0 +1,13 @@
+disallowed-types = [
+  # Inefficient. Use `.queue(…)` instead.
+  "crossterm::style::Stylize",
+  "crossterm::style::styled_content::StyledContent",
+]
+
+disallowed-methods = [
+  # We use `ahash` instead of the default hasher.
+  "std::collections::HashSet::new",
+  "std::collections::HashSet::with_capacity",
+  # Inefficient. Use `.queue(…)` instead.
+  "crossterm::style::style",
+]

dev/Cargo.toml

@@ -195,3 +195,25 @@ name = "exercises"
 edition = "2021"
 # Don't publish the exercises on crates.io!
 publish = false
+
+[profile.release]
+panic = "abort"
+
+[profile.dev]
+panic = "abort"
+
+[lints.rust]
+# You shouldn't write unsafe code in Rustlings
+unsafe_code = "forbid"
+# You don't need unstable features in Rustlings and shouldn't rely on them while learning Rust
+unstable_features = "forbid"
+
+[lints.clippy]
+# You forgot a `todo!()`
+todo = "forbid"
+# This can only happen by mistake in Rustlings
+empty_loop = "forbid"
+# No infinite loops are needed in Rustlings
+infinite_loop = "deny"
+# You shouldn't leak memory while still learning Rust
+mem_forget = "deny"

exercises/00_intro/intro1.rs

@@ -1,4 +1,4 @@
-// TODO: We sometimes encourage you to keep trying things on a given exercise,
+// TODO: We sometimes encourage you to keep trying things on a given exercise
 // even after you already figured it out. If you got everything working and feel
 // ready for the next exercise, enter `n` in the terminal.
 //
@@ -6,8 +6,7 @@
 // Try adding a new `println!` and check the updated output in the terminal.
 
 fn main() {
-    println!("Hello and");
-    println!(r#"       welcome to...                      "#);
+    println!(r#"       Welcome to...                      "#);
     println!(r#"                 _   _ _                  "#);
     println!(r#"  _ __ _   _ ___| |_| (_)_ __   __ _ ___  "#);
     println!(r#" | '__| | | / __| __| | | '_ \ / _` / __| "#);

exercises/01_variables/variables1.rs

@@ -1,5 +1,5 @@
 fn main() {
-    // TODO: Add missing keyword.
+    // TODO: Add the missing keyword.
     x = 5;
 
     println!("x has the value {x}");

exercises/02_functions/functions3.rs

@@ -1,4 +1,4 @@
-fn call_me(num: u32) {
+fn call_me(num: u8) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }

exercises/11_hashmaps/hashmaps2.rs

@@ -6,7 +6,7 @@
 // must add fruit to the basket so that there is at least one of each kind and
 // more than 11 in total - we have a lot of mouths to feed. You are not allowed
 // to insert any more of the fruits that are already in the basket (Apple,
-// Mango, and Lyche).
+// Mango, and Lychee).
 
 use std::collections::HashMap;
 

exercises/11_hashmaps/hashmaps3.rs

@@ -10,12 +10,12 @@ use std::collections::HashMap;
 
 // A structure to store the goal details of a team.
 #[derive(Default)]
-struct Team {
+struct TeamScores {
     goals_scored: u8,
     goals_conceded: u8,
 }
 
-fn build_scores_table(results: &str) -> HashMap<&str, Team> {
+fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
     // The name of the team is the key and its associated struct is the value.
     let mut scores = HashMap::new();
 

exercises/13_error_handling/errors1.rs

@@ -6,7 +6,7 @@
 // of `Option<String>`.
 fn generate_nametag_text(name: String) -> Option<String> {
     if name.is_empty() {
-        // Empty names aren't allowed.
+        // Empty names aren't allowed
         None
     } else {
         Some(format!("Hi! My name is {name}"))

exercises/13_error_handling/errors4.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::comparison_chain)]
-
 #[derive(PartialEq, Debug)]
 enum CreationError {
     Negative,

exercises/13_error_handling/errors6.rs

@@ -25,7 +25,7 @@ impl ParsePosNonzeroError {
     }
 
     // TODO: Add another error conversion function here.
-    // fn from_parseint(???) -> Self { ??? }
+    // fn from_parse_int(???) -> Self { ??? }
 }
 
 #[derive(PartialEq, Debug)]

exercises/17_tests/tests3.rs

@@ -9,7 +9,7 @@ impl Rectangle {
         if width <= 0 || height <= 0 {
             // Returning a `Result` would be better here. But we want to learn
             // how to test functions that can panic.
-            panic!("Rectangle width and height can't be negative");
+            panic!("Rectangle width and height must be positive");
         }
 
         Rectangle { width, height }

exercises/20_threads/threads3.rs

@@ -1,7 +1,6 @@
 use std::{sync::mpsc, thread, time::Duration};
 
 struct Queue {
-    length: u32,
     first_half: Vec<u32>,
     second_half: Vec<u32>,
 }
@@ -9,7 +8,6 @@ struct Queue {
 impl Queue {
     fn new() -> Self {
         Self {
-            length: 10,
             first_half: vec![1, 2, 3, 4, 5],
             second_half: vec![6, 7, 8, 9, 10],
         }
@@ -48,17 +46,15 @@ mod tests {
     fn threads3() {
         let (tx, rx) = mpsc::channel();
         let queue = Queue::new();
-        let queue_length = queue.length;
 
         send_tx(queue, tx);
 
-        let mut total_received: u32 = 0;
-        for received in rx {
-            println!("Got: {received}");
-            total_received += 1;
+        let mut received = Vec::with_capacity(10);
+        for value in rx {
+            received.push(value);
         }
 
-        println!("Number of received values: {total_received}");
-        assert_eq!(total_received, queue_length);
+        received.sort();
+        assert_eq!(received, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
     }
 }

exercises/quizzes/quiz2.rs

@@ -26,7 +26,7 @@ enum Command {
 mod my_module {
     use super::Command;
 
-    // TODO: Complete the function.
+    // TODO: Complete the function as described above.
     // pub fn transformer(input: ???) -> ??? { ??? }
 }
 

release-hook.sh

@@ -3,7 +3,11 @@
 # Error out if any command fails
 set -e
 
-cargo run -- dev check
 typos
-cargo outdated -w --exit-code 1
+cargo upgrades
+
+# Similar to CI
+cargo clippy -- --deny warnings
+cargo fmt --all --check
 cargo test --workspace --all-targets
+cargo run -- dev check --require-solutions

rustlings-macros/Cargo.toml

@@ -6,6 +6,7 @@ authors.workspace = true
 repository.workspace = true
 license.workspace = true
 edition.workspace = true
+rust-version.workspace = true
 include = [
   "/src/",
   "/info.toml",
@@ -15,6 +16,9 @@ include = [
 proc-macro = true
 
 [dependencies]
-quote = "1.0.36"
+quote = "1.0.37"
 serde.workspace = true
 toml_edit.workspace = true
+
+[lints]
+workspace = true

rustlings-macros/info.toml

@@ -498,7 +498,10 @@ some of them:
 https://doc.rust-lang.org/std/string/struct.String.html#method.trim
 
 For the `compose_me` method: You can either use the `format!` macro, or convert
-the string slice into an owned string, which you can then freely extend."""
+the string slice into an owned string, which you can then freely extend.
+
+For the `replace_me` method, you can check out the `replace` method:
+https://doc.rust-lang.org/std/string/struct.String.html#method.replace"""
 
 [[exercises]]
 name = "strings4"
@@ -568,7 +571,7 @@ name = "hashmaps3"
 dir = "11_hashmaps"
 hint = """
 Hint 1: Use the `entry()` and `or_insert()` (or `or_insert_with()`) methods of
-        `HashMap` to insert the default value of `Team` if a team doesn't
+        `HashMap` to insert the default value of `TeamScores` if a team doesn't
         exist in the table yet.
 
 Learn more in The Book:

solutions/02_functions/functions3.rs

@@ -1,4 +1,4 @@
-fn call_me(num: u32) {
+fn call_me(num: u8) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }

solutions/09_strings/strings4.rs

@@ -18,12 +18,11 @@ fn main() {
     // Here, both answers work.
     // `.into()` converts a type into an expected type.
     // If it is called where `String` is expected, it will convert `&str` to `String`.
-    // But if is called where `&str` is expected, then `&str` is kept `&str` since no
-    // conversion is needed.
     string("nice weather".into());
+    // But if it is called where `&str` is expected, then `&str` is kept `&str` since no conversion is needed.
+    // If you remove the `#[allow(…)]` line, then Clippy will tell you to remove `.into()` below since it is a useless conversion.
+    #[allow(clippy::useless_conversion)]
     string_slice("nice weather".into());
-    //                         ^^^^^^^ the compiler recommends removing the `.into()`
-    //                                 call because it is a useless conversion.
 
     string(format!("Interpolation {}", "Station"));
 

solutions/11_hashmaps/hashmaps2.rs

@@ -5,7 +5,8 @@
 // Apple (4), Mango (2) and Lychee (5) are already in the basket hash map. You
 // must add fruit to the basket so that there is at least one of each kind and
 // more than 11 in total - we have a lot of mouths to feed. You are not allowed
-// to insert any more of these fruits!
+// to insert any more of the fruits that are already in the basket (Apple,
+// Mango, and Lychee).
 
 use std::collections::HashMap;
 

solutions/11_hashmaps/hashmaps3.rs

@@ -10,12 +10,12 @@ use std::collections::HashMap;
 
 // A structure to store the goal details of a team.
 #[derive(Default)]
-struct Team {
+struct TeamScores {
     goals_scored: u8,
     goals_conceded: u8,
 }
 
-fn build_scores_table(results: &str) -> HashMap<&str, Team> {
+fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
     // The name of the team is the key and its associated struct is the value.
     let mut scores = HashMap::new();
 
@@ -28,13 +28,17 @@ fn build_scores_table(results: &str) -> HashMap<&str, Team> {
         let team_2_score: u8 = split_iterator.next().unwrap().parse().unwrap();
 
         // Insert the default with zeros if a team doesn't exist yet.
-        let team_1 = scores.entry(team_1_name).or_insert_with(Team::default);
+        let team_1 = scores
+            .entry(team_1_name)
+            .or_insert_with(TeamScores::default);
         // Update the values.
         team_1.goals_scored += team_1_score;
         team_1.goals_conceded += team_2_score;
 
-        // Similarely for the second team.
-        let team_2 = scores.entry(team_2_name).or_insert_with(Team::default);
+        // Similarly for the second team.
+        let team_2 = scores
+            .entry(team_2_name)
+            .or_insert_with(TeamScores::default);
         team_2.goals_scored += team_2_score;
         team_2.goals_conceded += team_1_score;
     }

solutions/13_error_handling/errors4.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::comparison_chain)]
+use std::cmp::Ordering;
 
 #[derive(PartialEq, Debug)]
 enum CreationError {
@@ -11,12 +11,10 @@ struct PositiveNonzeroInteger(u64);
 
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<Self, CreationError> {
-        if value == 0 {
-            Err(CreationError::Zero)
-        } else if value < 0 {
-            Err(CreationError::Negative)
-        } else {
-            Ok(Self(value as u64))
+        match value.cmp(&0) {
+            Ordering::Less => Err(CreationError::Negative),
+            Ordering::Equal => Err(CreationError::Zero),
+            Ordering::Greater => Ok(Self(value as u64)),
         }
     }
 }

solutions/13_error_handling/errors6.rs

@@ -24,7 +24,7 @@ impl ParsePosNonzeroError {
         Self::Creation(err)
     }
 
-    fn from_parseint(err: ParseIntError) -> Self {
+    fn from_parse_int(err: ParseIntError) -> Self {
         Self::ParseInt(err)
     }
 }
@@ -44,7 +44,7 @@ impl PositiveNonzeroInteger {
     fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
         // Return an appropriate error instead of panicking when `parse()`
         // returns an error.
-        let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
+        let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parse_int)?;
         //                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         Self::new(x).map_err(ParsePosNonzeroError::from_creation)
     }

solutions/17_tests/tests3.rs

@@ -9,7 +9,7 @@ impl Rectangle {
         if width <= 0 || height <= 0 {
             // Returning a `Result` would be better here. But we want to learn
             // how to test functions that can panic.
-            panic!("Rectangle width and height can't be negative");
+            panic!("Rectangle width and height must be positive");
         }
 
         Rectangle { width, height }

solutions/18_iterators/iterators4.rs

@@ -25,6 +25,7 @@ fn factorial_fold(num: u64) -> u64 {
     //              -> 1 * 2 is calculated, then the result 2 is multiplied by
     //                 the second element 3 so the result 6 is returned.
     // And so on…
+    #[allow(clippy::unnecessary_fold)]
     (2..=num).fold(1, |acc, x| acc * x)
 }
 

solutions/20_threads/threads3.rs

@@ -1,7 +1,6 @@
 use std::{sync::mpsc, thread, time::Duration};
 
 struct Queue {
-    length: u32,
     first_half: Vec<u32>,
     second_half: Vec<u32>,
 }
@@ -9,7 +8,6 @@ struct Queue {
 impl Queue {
     fn new() -> Self {
         Self {
-            length: 10,
             first_half: vec![1, 2, 3, 4, 5],
             second_half: vec![6, 7, 8, 9, 10],
         }
@@ -50,17 +48,15 @@ mod tests {
     fn threads3() {
         let (tx, rx) = mpsc::channel();
         let queue = Queue::new();
-        let queue_length = queue.length;
 
         send_tx(queue, tx);
 
-        let mut total_received: u32 = 0;
-        for received in rx {
-            println!("Got: {received}");
-            total_received += 1;
+        let mut received = Vec::with_capacity(10);
+        for value in rx {
+            received.push(value);
         }
 
-        println!("Number of received values: {total_received}");
-        assert_eq!(total_received, queue_length);
+        received.sort();
+        assert_eq!(received, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
     }
 }

solutions/README.md

@@ -0,0 +1,6 @@
+# Official Rustlings solutions
+
+Before you finish an exercise, its solution file will only contain an empty `main` function.
+The content of this file will be automatically replaced by the actual solution once you finish the exercise.
+
+Note that these solutions are often only _one possibility_ to solve an exercise.

src/app_state.rs

@@ -1,23 +1,23 @@
 use anyhow::{bail, Context, Result};
-use crossterm::style::Stylize;
-use serde::Deserialize;
 use std::{
-    fs::{self, File},
-    io::{Read, StdoutLock, Write},
-    path::{Path, PathBuf},
+    env,
+    fs::{File, OpenOptions},
+    io::{self, Read, Seek, StdoutLock, Write},
+    path::Path,
     process::{Command, Stdio},
+    thread,
 };
 
 use crate::{
     clear_terminal,
+    cmd::CmdRunner,
+    collections::hash_set_with_capacity,
     embedded::EMBEDDED_FILES,
-    exercise::{Exercise, RunnableExercise, OUTPUT_CAPACITY},
+    exercise::{Exercise, RunnableExercise},
     info_file::ExerciseInfo,
-    DEBUG_PROFILE,
 };
 
 const STATE_FILE_NAME: &str = ".rustlings-state.txt";
-const BAD_INDEX_ERR: &str = "The current exercise index is higher than the number of exercises";
 
 #[must_use]
 pub enum ExercisesProgress {
@@ -34,29 +34,10 @@ pub enum StateFileStatus {
     NotRead,
 }
 
-// Parses parts of the output of `cargo metadata`.
-#[derive(Deserialize)]
-struct CargoMetadata {
-    target_directory: PathBuf,
-}
-
-pub fn parse_target_dir() -> Result<PathBuf> {
-    // Get the target directory from Cargo.
-    let metadata_output = Command::new("cargo")
-        .arg("metadata")
-        .arg("-q")
-        .arg("--format-version")
-        .arg("1")
-        .arg("--no-deps")
-        .stdin(Stdio::null())
-        .stderr(Stdio::inherit())
-        .output()
-        .context(CARGO_METADATA_ERR)?
-        .stdout;
-
-    serde_json::de::from_slice::<CargoMetadata>(&metadata_output)
-        .context("Failed to read the field `target_directory` from the `cargo metadata` output")
-        .map(|metadata| metadata.target_directory)
+enum AllExercisesCheck {
+    Pending(usize),
+    AllDone,
+    CheckedUntil(usize),
 }
 
 pub struct AppState {
@@ -65,67 +46,32 @@ pub struct AppState {
     // Caches the number of done exercises to avoid iterating over all exercises every time.
     n_done: u16,
     final_message: String,
+    state_file: File,
     // Preallocated buffer for reading and writing the state file.
     file_buf: Vec<u8>,
     official_exercises: bool,
-    // Cargo's target directory.
-    target_dir: PathBuf,
+    cmd_runner: CmdRunner,
+    // Running in VS Code.
+    vs_code: bool,
 }
 
 impl AppState {
-    // Update the app state from the state file.
-    fn update_from_file(&mut self) -> StateFileStatus {
-        self.file_buf.clear();
-        self.n_done = 0;
-
-        if File::open(STATE_FILE_NAME)
-            .and_then(|mut file| file.read_to_end(&mut self.file_buf))
-            .is_err()
-        {
-            return StateFileStatus::NotRead;
-        }
-
-        // See `Self::write` for more information about the file format.
-        let mut lines = self.file_buf.split(|c| *c == b'\n').skip(2);
-
-        let Some(current_exercise_name) = lines.next() else {
-            return StateFileStatus::NotRead;
-        };
-
-        if current_exercise_name.is_empty() || lines.next().is_none() {
-            return StateFileStatus::NotRead;
-        }
-
-        let mut done_exercises = hashbrown::HashSet::with_capacity(self.exercises.len());
-
-        for done_exerise_name in lines {
-            if done_exerise_name.is_empty() {
-                break;
-            }
-            done_exercises.insert(done_exerise_name);
-        }
-
-        for (ind, exercise) in self.exercises.iter_mut().enumerate() {
-            if done_exercises.contains(exercise.name.as_bytes()) {
-                exercise.done = true;
-                self.n_done += 1;
-            }
-
-            if exercise.name.as_bytes() == current_exercise_name {
-                self.current_exercise_ind = ind;
-            }
-        }
-
-        StateFileStatus::Read
-    }
-
     pub fn new(
         exercise_infos: Vec<ExerciseInfo>,
         final_message: String,
     ) -> Result<(Self, StateFileStatus)> {
-        let target_dir = parse_target_dir()?;
+        let cmd_runner = CmdRunner::build()?;
+        let mut state_file = OpenOptions::new()
+            .create(true)
+            .read(true)
+            .write(true)
+            .truncate(false)
+            .open(STATE_FILE_NAME)
+            .with_context(|| {
+                format!("Failed to open or create the state file {STATE_FILE_NAME}")
+            })?;
 
-        let exercises = exercise_infos
+        let mut exercises = exercise_infos
             .into_iter()
             .map(|exercise_info| {
                 // Leaking to be able to borrow in the watch mode `Table`.
@@ -134,8 +80,7 @@ impl AppState {
                 let path = exercise_info.path().leak();
                 let name = exercise_info.name.leak();
                 let dir = exercise_info.dir.map(|dir| &*dir.leak());
-
-                let hint = exercise_info.hint.trim().to_owned();
+                let hint = exercise_info.hint.leak().trim_ascii();
 
                 Exercise {
                     dir,
@@ -144,23 +89,68 @@ impl AppState {
                     test: exercise_info.test,
                     strict_clippy: exercise_info.strict_clippy,
                     hint,
-                    // Updated in `Self::update_from_file`.
+                    // Updated below.
                     done: false,
                 }
             })
             .collect::<Vec<_>>();
 
-        let mut slf = Self {
-            current_exercise_ind: 0,
-            exercises,
-            n_done: 0,
-            final_message,
-            file_buf: Vec::with_capacity(2048),
-            official_exercises: !Path::new("info.toml").exists(),
-            target_dir,
+        let mut current_exercise_ind = 0;
+        let mut n_done = 0;
+        let mut file_buf = Vec::with_capacity(2048);
+        let state_file_status = 'block: {
+            if state_file.read_to_end(&mut file_buf).is_err() {
+                break 'block StateFileStatus::NotRead;
+            }
+
+            // See `Self::write` for more information about the file format.
+            let mut lines = file_buf.split(|c| *c == b'\n').skip(2);
+
+            let Some(current_exercise_name) = lines.next() else {
+                break 'block StateFileStatus::NotRead;
+            };
+
+            if current_exercise_name.is_empty() || lines.next().is_none() {
+                break 'block StateFileStatus::NotRead;
+            }
+
+            let mut done_exercises = hash_set_with_capacity(exercises.len());
+
+            for done_exerise_name in lines {
+                if done_exerise_name.is_empty() {
+                    break;
+                }
+                done_exercises.insert(done_exerise_name);
+            }
+
+            for (ind, exercise) in exercises.iter_mut().enumerate() {
+                if done_exercises.contains(exercise.name.as_bytes()) {
+                    exercise.done = true;
+                    n_done += 1;
+                }
+
+                if exercise.name.as_bytes() == current_exercise_name {
+                    current_exercise_ind = ind;
+                }
+            }
+
+            StateFileStatus::Read
         };
 
-        let state_file_status = slf.update_from_file();
+        file_buf.clear();
+        file_buf.extend_from_slice(STATE_FILE_HEADER);
+
+        let slf = Self {
+            current_exercise_ind,
+            exercises,
+            n_done,
+            final_message,
+            state_file,
+            file_buf,
+            official_exercises: !Path::new("info.toml").exists(),
+            cmd_runner,
+            vs_code: env::var_os("TERM_PROGRAM").is_some_and(|v| v == "vscode"),
+        };
 
         Ok((slf, state_file_status))
     }
@@ -186,8 +176,13 @@ impl AppState {
     }
 
     #[inline]
-    pub fn target_dir(&self) -> &Path {
-        &self.target_dir
+    pub fn cmd_runner(&self) -> &CmdRunner {
+        &self.cmd_runner
+    }
+
+    #[inline]
+    pub fn vs_code(&self) -> bool {
+        self.vs_code
     }
 
     // Write the state file.
@@ -199,10 +194,8 @@ impl AppState {
     // - The fourth line is an empty line.
     // - All remaining lines are the names of done exercises.
     fn write(&mut self) -> Result<()> {
-        self.file_buf.clear();
+        self.file_buf.truncate(STATE_FILE_HEADER.len());
 
-        self.file_buf
-            .extend_from_slice(b"DON'T EDIT THIS FILE!\n\n");
         self.file_buf
             .extend_from_slice(self.current_exercise().name.as_bytes());
         self.file_buf.push(b'\n');
@@ -214,7 +207,14 @@ impl AppState {
             }
         }
 
-        fs::write(STATE_FILE_NAME, &self.file_buf)
+        self.state_file
+            .rewind()
+            .with_context(|| format!("Failed to rewind the state file {STATE_FILE_NAME}"))?;
+        self.state_file
+            .set_len(0)
+            .with_context(|| format!("Failed to truncate the state file {STATE_FILE_NAME}"))?;
+        self.state_file
+            .write_all(&self.file_buf)
             .with_context(|| format!("Failed to write the state file {STATE_FILE_NAME}"))?;
 
         Ok(())
@@ -298,6 +298,7 @@ impl AppState {
         Ok(exercise.path)
     }
 
+    // Reset the exercise by index and return its name.
     pub fn reset_exercise_by_ind(&mut self, exercise_ind: usize) -> Result<&'static str> {
         if exercise_ind >= self.exercises.len() {
             bail!(BAD_INDEX_ERR);
@@ -307,36 +308,33 @@ impl AppState {
         let exercise = &self.exercises[exercise_ind];
         self.reset(exercise_ind, exercise.path)?;
 
-        Ok(exercise.path)
+        Ok(exercise.name)
     }
 
     // Return the index of the next pending exercise or `None` if all exercises are done.
     fn next_pending_exercise_ind(&self) -> Option<usize> {
-        if self.current_exercise_ind == self.exercises.len() - 1 {
-            // The last exercise is done.
-            // Search for exercises not done from the start.
-            return self.exercises[..self.current_exercise_ind]
-                .iter()
-                .position(|exercise| !exercise.done);
-        }
-
-        // The done exercise isn't the last one.
-        // Search for a pending exercise after the current one and then from the start.
-        match self.exercises[self.current_exercise_ind + 1..]
-            .iter()
-            .position(|exercise| !exercise.done)
-        {
-            Some(ind) => Some(self.current_exercise_ind + 1 + ind),
-            None => self.exercises[..self.current_exercise_ind]
-                .iter()
-                .position(|exercise| !exercise.done),
-        }
+        let next_ind = self.current_exercise_ind + 1;
+        self.exercises
+            // If the exercise done isn't the last, search for pending exercises after it.
+            .get(next_ind..)
+            .and_then(|later_exercises| {
+                later_exercises
+                    .iter()
+                    .position(|exercise| !exercise.done)
+                    .map(|ind| next_ind + ind)
+            })
+            // Search from the start.
+            .or_else(|| {
+                self.exercises[..self.current_exercise_ind]
+                    .iter()
+                    .position(|exercise| !exercise.done)
+            })
     }
 
     /// Official exercises: Dump the solution file form the binary and return its path.
     /// Third-party exercises: Check if a solution file exists and return its path in that case.
     pub fn current_solution_path(&self) -> Result<Option<String>> {
-        if DEBUG_PROFILE {
+        if cfg!(debug_assertions) {
             return Ok(None);
         }
 
@@ -347,24 +345,72 @@ impl AppState {
                 .write_solution_to_disk(self.current_exercise_ind, current_exercise.name)
                 .map(Some)
         } else {
-            let solution_path = if let Some(dir) = current_exercise.dir {
-                format!("solutions/{dir}/{}.rs", current_exercise.name)
-            } else {
-                format!("solutions/{}.rs", current_exercise.name)
-            };
+            let sol_path = current_exercise.sol_path();
 
-            if Path::new(&solution_path).exists() {
-                return Ok(Some(solution_path));
+            if Path::new(&sol_path).exists() {
+                return Ok(Some(sol_path));
             }
 
             Ok(None)
         }
     }
 
+    // Return the exercise index of the first pending exercise found.
+    fn check_all_exercises(&self, stdout: &mut StdoutLock) -> Result<Option<usize>> {
+        stdout.write_all(RERUNNING_ALL_EXERCISES_MSG)?;
+        let n_exercises = self.exercises.len();
+
+        let status = thread::scope(|s| {
+            let handles = self
+                .exercises
+                .iter()
+                .map(|exercise| s.spawn(|| exercise.run_exercise(None, &self.cmd_runner)))
+                .collect::<Vec<_>>();
+
+            for (exercise_ind, handle) in handles.into_iter().enumerate() {
+                write!(stdout, "\rProgress: {exercise_ind}/{n_exercises}")?;
+                stdout.flush()?;
+
+                let Ok(success) = handle.join().unwrap() else {
+                    return Ok(AllExercisesCheck::CheckedUntil(exercise_ind));
+                };
+
+                if !success {
+                    return Ok(AllExercisesCheck::Pending(exercise_ind));
+                }
+            }
+
+            Ok::<_, io::Error>(AllExercisesCheck::AllDone)
+        })?;
+
+        let mut exercise_ind = match status {
+            AllExercisesCheck::Pending(exercise_ind) => return Ok(Some(exercise_ind)),
+            AllExercisesCheck::AllDone => return Ok(None),
+            AllExercisesCheck::CheckedUntil(ind) => ind,
+        };
+
+        // We got an error while checking all exercises in parallel.
+        // This could be because we exceeded the limit of open file descriptors.
+        // Therefore, try to continue the check sequentially.
+        for exercise in &self.exercises[exercise_ind..] {
+            write!(stdout, "\rProgress: {exercise_ind}/{n_exercises}")?;
+            stdout.flush()?;
+
+            let success = exercise.run_exercise(None, &self.cmd_runner)?;
+            if !success {
+                return Ok(Some(exercise_ind));
+            }
+
+            exercise_ind += 1;
+        }
+
+        Ok(None)
+    }
+
     /// Mark the current exercise as done and move on to the next pending exercise if one exists.
     /// If all exercises are marked as done, run all of them to make sure that they are actually
     /// done. If an exercise which is marked as done fails, mark it as pending and continue on it.
-    pub fn done_current_exercise(&mut self, writer: &mut StdoutLock) -> Result<ExercisesProgress> {
+    pub fn done_current_exercise(&mut self, stdout: &mut StdoutLock) -> Result<ExercisesProgress> {
         let exercise = &mut self.exercises[self.current_exercise_ind];
         if !exercise.done {
             exercise.done = true;
@@ -373,62 +419,42 @@ impl AppState {
 
         if let Some(ind) = self.next_pending_exercise_ind() {
             self.set_current_exercise_ind(ind)?;
-
             return Ok(ExercisesProgress::NewPending);
         }
 
-        writer.write_all(RERUNNING_ALL_EXERCISES_MSG)?;
+        if let Some(pending_exercise_ind) = self.check_all_exercises(stdout)? {
+            stdout.write_all(b"\n\n")?;
 
-        let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-        for (exercise_ind, exercise) in self.exercises().iter().enumerate() {
-            write!(writer, "Running {exercise} ... ")?;
-            writer.flush()?;
-
-            let success = exercise.run_exercise(&mut output, &self.target_dir)?;
-            if !success {
-                writeln!(writer, "{}\n", "FAILED".red())?;
-
-                self.current_exercise_ind = exercise_ind;
-
-                // No check if the exercise is done before setting it to pending
-                // because no pending exercise was found.
-                self.exercises[exercise_ind].done = false;
-                self.n_done -= 1;
-
-                self.write()?;
-
-                return Ok(ExercisesProgress::NewPending);
-            }
-
-            writeln!(writer, "{}", "ok".green())?;
+            self.current_exercise_ind = pending_exercise_ind;
+            self.exercises[pending_exercise_ind].done = false;
+            // All exercises were marked as done.
+            self.n_done -= 1;
+            self.write()?;
+            return Ok(ExercisesProgress::NewPending);
         }
 
         // Write that the last exercise is done.
         self.write()?;
 
-        clear_terminal(writer)?;
-        writer.write_all(FENISH_LINE.as_bytes())?;
+        clear_terminal(stdout)?;
+        stdout.write_all(FENISH_LINE.as_bytes())?;
 
-        let final_message = self.final_message.trim();
+        let final_message = self.final_message.trim_ascii();
         if !final_message.is_empty() {
-            writer.write_all(final_message.as_bytes())?;
-            writer.write_all(b"\n")?;
+            stdout.write_all(final_message.as_bytes())?;
+            stdout.write_all(b"\n")?;
         }
 
         Ok(ExercisesProgress::AllDone)
     }
 }
 
-const CARGO_METADATA_ERR: &str = "Failed to run the command `cargo metadata …`
-Did you already install Rust?
-Try running `cargo --version` to diagnose the problem.";
-
+const BAD_INDEX_ERR: &str = "The current exercise index is higher than the number of exercises";
+const STATE_FILE_HEADER: &[u8] = b"DON'T EDIT THIS FILE!\n\n";
 const RERUNNING_ALL_EXERCISES_MSG: &[u8] = b"
 All exercises seem to be done.
 Recompiling and running all exercises to make sure that all of them are actually done.
-
 ";
-
 const FENISH_LINE: &str = "+----------------------------------------------------+
 |          You made it to the Fe-nish line!          |
 +--------------------------  ------------------------+
@@ -462,7 +488,7 @@ mod tests {
             path: "exercises/0.rs",
             test: false,
             strict_clippy: false,
-            hint: String::new(),
+            hint: "",
             done: false,
         }
     }
@@ -474,9 +500,11 @@ mod tests {
             exercises: vec![dummy_exercise(), dummy_exercise(), dummy_exercise()],
             n_done: 0,
             final_message: String::new(),
+            state_file: tempfile::tempfile().unwrap(),
             file_buf: Vec::new(),
             official_exercises: true,
-            target_dir: PathBuf::new(),
+            cmd_runner: CmdRunner::build().unwrap(),
+            vs_code: false,
         };
 
         let mut assert = |done: [bool; 3], expected: [Option<usize>; 3]| {

src/cargo_toml.rs

@@ -1,7 +1,7 @@
 use anyhow::{Context, Result};
 use std::path::Path;
 
-use crate::info_file::ExerciseInfo;
+use crate::{exercise::RunnableExercise, info_file::ExerciseInfo};
 
 /// Initial capacity of the bins buffer.
 pub const BINS_BUFFER_CAPACITY: usize = 1 << 14;

src/cmd.rs

@@ -1,30 +1,44 @@
-use anyhow::{Context, Result};
-use std::{io::Read, path::Path, process::Command};
+use anyhow::{bail, Context, Result};
+use serde::Deserialize;
+use std::{
+    io::Read,
+    path::PathBuf,
+    process::{Command, Stdio},
+};
 
 /// Run a command with a description for a possible error and append the merged stdout and stderr.
 /// The boolean in the returned `Result` is true if the command's exit status is success.
-pub fn run_cmd(mut cmd: Command, description: &str, output: &mut Vec<u8>) -> Result<bool> {
-    let (mut reader, writer) = os_pipe::pipe()
-        .with_context(|| format!("Failed to create a pipe to run the command `{description}``"))?;
+fn run_cmd(mut cmd: Command, description: &str, output: Option<&mut Vec<u8>>) -> Result<bool> {
+    let spawn = |mut cmd: Command| {
+        // NOTE: The closure drops `cmd` which prevents a pipe deadlock.
+        cmd.stdin(Stdio::null())
+            .spawn()
+            .with_context(|| format!("Failed to run the command `{description}`"))
+    };
 
-    let writer_clone = writer.try_clone().with_context(|| {
-        format!("Failed to clone the pipe writer for the command `{description}`")
-    })?;
+    let mut handle = if let Some(output) = output {
+        let (mut reader, writer) = os_pipe::pipe().with_context(|| {
+            format!("Failed to create a pipe to run the command `{description}``")
+        })?;
 
-    let mut handle = cmd
-        .stdout(writer_clone)
-        .stderr(writer)
-        .spawn()
-        .with_context(|| format!("Failed to run the command `{description}`"))?;
+        let writer_clone = writer.try_clone().with_context(|| {
+            format!("Failed to clone the pipe writer for the command `{description}`")
+        })?;
 
-    // Prevent pipe deadlock.
-    drop(cmd);
+        cmd.stdout(writer_clone).stderr(writer);
+        let handle = spawn(cmd)?;
 
-    reader
-        .read_to_end(output)
-        .with_context(|| format!("Failed to read the output of the command `{description}`"))?;
+        reader
+            .read_to_end(output)
+            .with_context(|| format!("Failed to read the output of the command `{description}`"))?;
 
-    output.push(b'\n');
+        output.push(b'\n');
+
+        handle
+    } else {
+        cmd.stdout(Stdio::null()).stderr(Stdio::null());
+        spawn(cmd)?
+    };
 
     handle
         .wait()
@@ -32,50 +46,106 @@ pub fn run_cmd(mut cmd: Command, description: &str, output: &mut Vec<u8>) -> Res
         .map(|status| status.success())
 }
 
-pub struct CargoCmd<'a> {
-    pub subcommand: &'a str,
-    pub args: &'a [&'a str],
-    pub bin_name: &'a str,
-    pub description: &'a str,
-    /// RUSTFLAGS="-A warnings"
-    pub hide_warnings: bool,
-    /// Added as `--target-dir` if `Self::dev` is true.
-    pub target_dir: &'a Path,
-    /// The output buffer to append the merged stdout and stderr.
-    pub output: &'a mut Vec<u8>,
-    /// true while developing Rustlings.
-    pub dev: bool,
+// Parses parts of the output of `cargo metadata`.
+#[derive(Deserialize)]
+struct CargoMetadata {
+    target_directory: PathBuf,
 }
 
-impl<'a> CargoCmd<'a> {
-    /// Run `cargo SUBCOMMAND --bin EXERCISE_NAME … ARGS`.
-    pub fn run(&mut self) -> Result<bool> {
+pub struct CmdRunner {
+    target_dir: PathBuf,
+}
+
+impl CmdRunner {
+    pub fn build() -> Result<Self> {
+        // Get the target directory from Cargo.
+        let metadata_output = Command::new("cargo")
+            .arg("metadata")
+            .arg("-q")
+            .arg("--format-version")
+            .arg("1")
+            .arg("--no-deps")
+            .stdin(Stdio::null())
+            .stderr(Stdio::inherit())
+            .output()
+            .context(CARGO_METADATA_ERR)?;
+
+        if !metadata_output.status.success() {
+            bail!("The command `cargo metadata …` failed. Are you in the `rustlings/` directory?");
+        }
+
+        let metadata: CargoMetadata = serde_json::de::from_slice(&metadata_output.stdout)
+            .context(
+                "Failed to read the field `target_directory` from the output of the command `cargo metadata …`",
+            )?;
+
+        Ok(Self {
+            target_dir: metadata.target_directory,
+        })
+    }
+
+    pub fn cargo<'out>(
+        &self,
+        subcommand: &str,
+        bin_name: &str,
+        output: Option<&'out mut Vec<u8>>,
+    ) -> CargoSubcommand<'out> {
         let mut cmd = Command::new("cargo");
-        cmd.arg(self.subcommand);
+        cmd.arg(subcommand).arg("-q").arg("--bin").arg(bin_name);
 
         // A hack to make `cargo run` work when developing Rustlings.
-        if self.dev {
-            cmd.arg("--manifest-path")
-                .arg("dev/Cargo.toml")
-                .arg("--target-dir")
-                .arg(self.target_dir);
+        #[cfg(debug_assertions)]
+        cmd.arg("--manifest-path")
+            .arg("dev/Cargo.toml")
+            .arg("--target-dir")
+            .arg(&self.target_dir);
+
+        if output.is_some() {
+            cmd.arg("--color").arg("always");
         }
 
-        cmd.arg("--color")
-            .arg("always")
-            .arg("-q")
-            .arg("--bin")
-            .arg(self.bin_name)
-            .args(self.args);
+        CargoSubcommand { cmd, output }
+    }
 
-        if self.hide_warnings {
-            cmd.env("RUSTFLAGS", "-A warnings");
-        }
+    /// The boolean in the returned `Result` is true if the command's exit status is success.
+    pub fn run_debug_bin(&self, bin_name: &str, output: Option<&mut Vec<u8>>) -> Result<bool> {
+        // 7 = "/debug/".len()
+        let mut bin_path =
+            PathBuf::with_capacity(self.target_dir.as_os_str().len() + 7 + bin_name.len());
+        bin_path.push(&self.target_dir);
+        bin_path.push("debug");
+        bin_path.push(bin_name);
 
-        run_cmd(cmd, self.description, self.output)
+        run_cmd(Command::new(&bin_path), &bin_path.to_string_lossy(), output)
     }
 }
 
+pub struct CargoSubcommand<'out> {
+    cmd: Command,
+    output: Option<&'out mut Vec<u8>>,
+}
+
+impl<'out> CargoSubcommand<'out> {
+    #[inline]
+    pub fn args<'arg, I>(&mut self, args: I) -> &mut Self
+    where
+        I: IntoIterator<Item = &'arg str>,
+    {
+        self.cmd.args(args);
+        self
+    }
+
+    /// The boolean in the returned `Result` is true if the command's exit status is success.
+    #[inline]
+    pub fn run(self, description: &str) -> Result<bool> {
+        run_cmd(self.cmd, description, self.output)
+    }
+}
+
+const CARGO_METADATA_ERR: &str = "Failed to run the command `cargo metadata …`
+Did you already install Rust?
+Try running `cargo --version` to diagnose the problem.";
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -86,7 +156,7 @@ mod tests {
         cmd.arg("Hello");
 
         let mut output = Vec::with_capacity(8);
-        run_cmd(cmd, "echo …", &mut output).unwrap();
+        run_cmd(cmd, "echo …", Some(&mut output)).unwrap();
 
         assert_eq!(output, b"Hello\n\n");
     }

src/collections.rs

@@ -0,0 +1,10 @@
+use ahash::AHasher;
+use std::hash::BuildHasherDefault;
+
+/// DOS attacks aren't a concern for Rustlings. Therefore, we use `ahash` with fixed seeds.
+pub type HashSet<T> = std::collections::HashSet<T, BuildHasherDefault<AHasher>>;
+
+#[inline]
+pub fn hash_set_with_capacity<T>(capacity: usize) -> HashSet<T> {
+    HashSet::with_capacity_and_hasher(capacity, BuildHasherDefault::<AHasher>::default())
+}

src/dev.rs

@@ -2,8 +2,6 @@ use anyhow::{bail, Context, Result};
 use clap::Subcommand;
 use std::path::PathBuf;
 
-use crate::DEBUG_PROFILE;
-
 mod check;
 mod new;
 mod update;
@@ -32,7 +30,7 @@ impl DevCommands {
     pub fn run(self) -> Result<()> {
         match self {
             Self::New { path, no_git } => {
-                if DEBUG_PROFILE {
+                if cfg!(debug_assertions) {
                     bail!("Disabled in the debug build");
                 }
 

src/dev/check.rs

@@ -1,56 +1,59 @@
-use anyhow::{anyhow, bail, Context, Result};
+use anyhow::{anyhow, bail, Context, Error, Result};
 use std::{
     cmp::Ordering,
     fs::{self, read_dir, OpenOptions},
     io::{self, Read, Write},
     path::{Path, PathBuf},
-    sync::{
-        atomic::{self, AtomicBool},
-        Mutex,
-    },
+    process::{Command, Stdio},
     thread,
 };
 
 use crate::{
-    app_state::parse_target_dir,
     cargo_toml::{append_bins, bins_start_end_ind, BINS_BUFFER_CAPACITY},
+    cmd::CmdRunner,
+    collections::{hash_set_with_capacity, HashSet},
     exercise::{RunnableExercise, OUTPUT_CAPACITY},
     info_file::{ExerciseInfo, InfoFile},
-    CURRENT_FORMAT_VERSION, DEBUG_PROFILE,
+    CURRENT_FORMAT_VERSION,
 };
 
+const MAX_EXERCISE_NAME_LEN: usize = 32;
+
 // Find a char that isn't allowed in the exercise's `name` or `dir`.
 fn forbidden_char(input: &str) -> Option<char> {
     input.chars().find(|c| !c.is_alphanumeric() && *c != '_')
 }
 
-// Check that the Cargo.toml file is up-to-date.
+// Check that the `Cargo.toml` file is up-to-date.
 fn check_cargo_toml(
     exercise_infos: &[ExerciseInfo],
-    current_cargo_toml: &str,
+    cargo_toml_path: &str,
     exercise_path_prefix: &[u8],
 ) -> Result<()> {
-    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+    let current_cargo_toml = fs::read_to_string(cargo_toml_path)
+        .with_context(|| format!("Failed to read the file `{cargo_toml_path}`"))?;
+
+    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(&current_cargo_toml)?;
 
     let old_bins = &current_cargo_toml.as_bytes()[bins_start_ind..bins_end_ind];
     let mut new_bins = Vec::with_capacity(BINS_BUFFER_CAPACITY);
     append_bins(&mut new_bins, exercise_infos, exercise_path_prefix);
 
     if old_bins != new_bins {
-        if DEBUG_PROFILE {
-            bail!("The file `dev/Cargo.toml` is outdated. Please run `cargo run -- dev update` to update it");
+        if cfg!(debug_assertions) {
+            bail!("The file `dev/Cargo.toml` is outdated. Please run `cargo run -- dev update` to update it. Then run `cargo run -- dev check` again");
         }
 
-        bail!("The file `Cargo.toml` is outdated. Please run `rustlings dev update` to update it");
+        bail!("The file `Cargo.toml` is outdated. Please run `rustlings dev update` to update it. Then run `rustlings dev check` again");
     }
 
     Ok(())
 }
 
 // Check the info of all exercises and return their paths in a set.
-fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<PathBuf>> {
-    let mut names = hashbrown::HashSet::with_capacity(info_file.exercises.len());
-    let mut paths = hashbrown::HashSet::with_capacity(info_file.exercises.len());
+fn check_info_file_exercises(info_file: &InfoFile) -> Result<HashSet<PathBuf>> {
+    let mut names = hash_set_with_capacity(info_file.exercises.len());
+    let mut paths = hash_set_with_capacity(info_file.exercises.len());
 
     let mut file_buf = String::with_capacity(1 << 14);
     for exercise_info in &info_file.exercises {
@@ -58,6 +61,9 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
         if name.is_empty() {
             bail!("Found an empty exercise name in `info.toml`");
         }
+        if name.len() > MAX_EXERCISE_NAME_LEN {
+            bail!("The length of the exercise name `{name}` is bigger than the maximum {MAX_EXERCISE_NAME_LEN}");
+        }
         if let Some(c) = forbidden_char(name) {
             bail!("Char `{c}` in the exercise name `{name}` is not allowed");
         }
@@ -71,7 +77,7 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
             }
         }
 
-        if exercise_info.hint.trim().is_empty() {
+        if exercise_info.hint.trim_ascii().is_empty() {
             bail!("The exercise `{name}` has an empty hint. Please provide a hint or at least tell the user why a hint isn't needed for this exercise");
         }
 
@@ -96,7 +102,12 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
             bail!("Didn't find any `// TODO` comment in the file `{path}`.\nYou need to have at least one such comment to guide the user.");
         }
 
-        if !exercise_info.test && file_buf.contains("#[test]") {
+        let contains_tests = file_buf.contains("#[test]\n");
+        if exercise_info.test {
+            if !contains_tests {
+                bail!("The file `{path}` doesn't contain any tests. If you don't want to add tests to this exercise, set `test = false` for this exercise in the `info.toml` file");
+            }
+        } else if contains_tests {
             bail!("The file `{path}` contains tests annotated with `#[test]` but the exercise `{name}` has `test = false` in the `info.toml` file");
         }
 
@@ -111,10 +122,7 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
 // Check `dir` for unexpected files.
 // Only Rust files in `allowed_rust_files` and `README.md` files are allowed.
 // Only one level of directory nesting is allowed.
-fn check_unexpected_files(
-    dir: &str,
-    allowed_rust_files: &hashbrown::HashSet<PathBuf>,
-) -> Result<()> {
+fn check_unexpected_files(dir: &str, allowed_rust_files: &HashSet<PathBuf>) -> Result<()> {
     let unexpected_file = |path: &Path| {
         anyhow!("Found the file `{}`. Only `README.md` and Rust files related to an exercise in `info.toml` are allowed in the `{dir}` directory", path.display())
     };
@@ -162,135 +170,191 @@ fn check_unexpected_files(
     Ok(())
 }
 
-fn check_exercises_unsolved(info_file: &InfoFile, target_dir: &Path) -> Result<()> {
-    let error_occurred = AtomicBool::new(false);
+fn check_exercises_unsolved(
+    info_file: &'static InfoFile,
+    cmd_runner: &'static CmdRunner,
+) -> Result<()> {
+    let mut stdout = io::stdout().lock();
+    stdout.write_all(b"Running all exercises to check that they aren't already solved...\n")?;
 
-    println!(
-        "Running all exercises to check that they aren't already solved. This may take a while…\n",
-    );
-    thread::scope(|s| {
-        for exercise_info in &info_file.exercises {
+    let handles = info_file
+        .exercises
+        .iter()
+        .filter_map(|exercise_info| {
             if exercise_info.skip_check_unsolved {
-                continue;
+                return None;
             }
 
-            s.spawn(|| {
-                let error = |e| {
-                    let mut stderr = io::stderr().lock();
-                    stderr.write_all(e).unwrap();
-                    stderr.write_all(b"\nProblem with the exercise ").unwrap();
-                    stderr.write_all(exercise_info.name.as_bytes()).unwrap();
-                    stderr.write_all(SEPARATOR).unwrap();
-                    error_occurred.store(true, atomic::Ordering::Relaxed);
-                };
+            Some((
+                exercise_info.name.as_str(),
+                thread::spawn(|| exercise_info.run_exercise(None, cmd_runner)),
+            ))
+        })
+        .collect::<Vec<_>>();
 
-                let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-                match exercise_info.run_exercise(&mut output, target_dir) {
-                    Ok(true) => error(b"Already solved!"),
-                    Ok(false) => (),
-                    Err(e) => error(e.to_string().as_bytes()),
-                }
-            });
+    let n_handles = handles.len();
+    write!(stdout, "Progress: 0/{n_handles}")?;
+    stdout.flush()?;
+    let mut handle_num = 1;
+
+    for (exercise_name, handle) in handles {
+        let Ok(result) = handle.join() else {
+            bail!("Panic while trying to run the exericse {exercise_name}");
+        };
+
+        match result {
+            Ok(true) => {
+                bail!("The exercise {exercise_name} is already solved.\n{SKIP_CHECK_UNSOLVED_HINT}",)
+            }
+            Ok(false) => (),
+            Err(e) => return Err(e),
         }
-    });
 
-    if error_occurred.load(atomic::Ordering::Relaxed) {
-        bail!(CHECK_EXERCISES_UNSOLVED_ERR);
+        write!(stdout, "\rProgress: {handle_num}/{n_handles}")?;
+        stdout.flush()?;
+        handle_num += 1;
     }
+    stdout.write_all(b"\n")?;
 
     Ok(())
 }
 
-fn check_exercises(info_file: &InfoFile, target_dir: &Path) -> Result<()> {
+fn check_exercises(info_file: &'static InfoFile, cmd_runner: &'static CmdRunner) -> Result<()> {
     match info_file.format_version.cmp(&CURRENT_FORMAT_VERSION) {
         Ordering::Less => bail!("`format_version` < {CURRENT_FORMAT_VERSION} (supported version)\nPlease migrate to the latest format version"),
         Ordering::Greater => bail!("`format_version` > {CURRENT_FORMAT_VERSION} (supported version)\nTry updating the Rustlings program"),
         Ordering::Equal => (),
     }
 
+    let handle = thread::spawn(move || check_exercises_unsolved(info_file, cmd_runner));
+
     let info_file_paths = check_info_file_exercises(info_file)?;
     check_unexpected_files("exercises", &info_file_paths)?;
 
-    check_exercises_unsolved(info_file, target_dir)
+    handle.join().unwrap()
 }
 
-fn check_solutions(require_solutions: bool, info_file: &InfoFile, target_dir: &Path) -> Result<()> {
-    let paths = Mutex::new(hashbrown::HashSet::with_capacity(info_file.exercises.len()));
-    let error_occurred = AtomicBool::new(false);
+enum SolutionCheck {
+    Success { sol_path: String },
+    MissingOptional,
+    RunFailure { output: Vec<u8> },
+    Err(Error),
+}
 
-    println!("Running all solutions. This may take a while…\n");
-    thread::scope(|s| {
-        for exercise_info in &info_file.exercises {
-            s.spawn(|| {
-                let error = |e| {
-                    let mut stderr = io::stderr().lock();
-                    stderr.write_all(e).unwrap();
-                    stderr
-                        .write_all(b"\nFailed to run the solution of the exercise ")
-                        .unwrap();
-                    stderr.write_all(exercise_info.name.as_bytes()).unwrap();
-                    stderr.write_all(SEPARATOR).unwrap();
-                    error_occurred.store(true, atomic::Ordering::Relaxed);
-                };
+fn check_solutions(
+    require_solutions: bool,
+    info_file: &'static InfoFile,
+    cmd_runner: &'static CmdRunner,
+) -> Result<()> {
+    let mut stdout = io::stdout().lock();
+    stdout.write_all(b"Running all solutions...\n")?;
 
-                let path = exercise_info.sol_path();
-                if !Path::new(&path).exists() {
+    let handles = info_file
+        .exercises
+        .iter()
+        .map(|exercise_info| {
+            thread::spawn(move || {
+                let sol_path = exercise_info.sol_path();
+                if !Path::new(&sol_path).exists() {
                     if require_solutions {
-                        error(b"Solution missing");
+                        return SolutionCheck::Err(anyhow!(
+                            "The solution of the exercise {} is missing",
+                            exercise_info.name,
+                        ));
                     }
 
-                    // No solution to check.
-                    return;
+                    return SolutionCheck::MissingOptional;
                 }
 
                 let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-                match exercise_info.run_solution(&mut output, target_dir) {
-                    Ok(true) => {
-                        paths.lock().unwrap().insert(PathBuf::from(path));
-                    }
-                    Ok(false) => error(&output),
-                    Err(e) => error(e.to_string().as_bytes()),
+                match exercise_info.run_solution(Some(&mut output), cmd_runner) {
+                    Ok(true) => SolutionCheck::Success { sol_path },
+                    Ok(false) => SolutionCheck::RunFailure { output },
+                    Err(e) => SolutionCheck::Err(e),
                 }
-            });
-        }
-    });
+            })
+        })
+        .collect::<Vec<_>>();
 
-    if error_occurred.load(atomic::Ordering::Relaxed) {
-        bail!("At least one solution failed. See the output above.");
+    let mut sol_paths = hash_set_with_capacity(info_file.exercises.len());
+    let mut fmt_cmd = Command::new("rustfmt");
+    fmt_cmd
+        .arg("--check")
+        .arg("--edition")
+        .arg("2021")
+        .arg("--color")
+        .arg("always")
+        .stdin(Stdio::null());
+
+    let n_handles = handles.len();
+    write!(stdout, "Progress: 0/{n_handles}")?;
+    stdout.flush()?;
+    let mut handle_num = 1;
+
+    for (exercise_info, handle) in info_file.exercises.iter().zip(handles) {
+        let Ok(check_result) = handle.join() else {
+            bail!(
+                "Panic while trying to run the solution of the exericse {}",
+                exercise_info.name,
+            );
+        };
+
+        match check_result {
+            SolutionCheck::Success { sol_path } => {
+                fmt_cmd.arg(&sol_path);
+                sol_paths.insert(PathBuf::from(sol_path));
+            }
+            SolutionCheck::MissingOptional => (),
+            SolutionCheck::RunFailure { output } => {
+                stdout.write_all(b"\n\n")?;
+                stdout.write_all(&output)?;
+                bail!(
+                    "Running the solution of the exercise {} failed with the error above",
+                    exercise_info.name,
+                );
+            }
+            SolutionCheck::Err(e) => return Err(e),
+        }
+
+        write!(stdout, "\rProgress: {handle_num}/{n_handles}")?;
+        stdout.flush()?;
+        handle_num += 1;
+    }
+    stdout.write_all(b"\n")?;
+
+    let handle = thread::spawn(move || check_unexpected_files("solutions", &sol_paths));
+
+    if !fmt_cmd
+        .status()
+        .context("Failed to run `rustfmt` on all solution files")?
+        .success()
+    {
+        bail!("Some solutions aren't formatted. Run `rustfmt` on them");
     }
 
-    check_unexpected_files("solutions", &paths.into_inner().unwrap())?;
-
-    Ok(())
+    handle.join().unwrap()
 }
 
 pub fn check(require_solutions: bool) -> Result<()> {
     let info_file = InfoFile::parse()?;
 
-    // A hack to make `cargo run -- dev check` work when developing Rustlings.
-    if DEBUG_PROFILE {
-        check_cargo_toml(
-            &info_file.exercises,
-            include_str!("../../dev-Cargo.toml"),
-            b"../",
-        )?;
+    if cfg!(debug_assertions) {
+        // A hack to make `cargo run -- dev check` work when developing Rustlings.
+        check_cargo_toml(&info_file.exercises, "dev/Cargo.toml", b"../")?;
     } else {
-        let current_cargo_toml =
-            fs::read_to_string("Cargo.toml").context("Failed to read the file `Cargo.toml`")?;
-        check_cargo_toml(&info_file.exercises, &current_cargo_toml, b"")?;
+        check_cargo_toml(&info_file.exercises, "Cargo.toml", b"")?;
     }
 
-    let target_dir = parse_target_dir()?;
-    check_exercises(&info_file, &target_dir)?;
-    check_solutions(require_solutions, &info_file, &target_dir)?;
+    // Leaking is fine since they are used until the end of the program.
+    let cmd_runner = Box::leak(Box::new(CmdRunner::build()?));
+    let info_file = Box::leak(Box::new(info_file));
 
-    println!("\nEverything looks fine!");
+    check_exercises(info_file, cmd_runner)?;
+    check_solutions(require_solutions, info_file, cmd_runner)?;
+
+    println!("Everything looks fine!");
 
     Ok(())
 }
 
-const SEPARATOR: &[u8] =
-    b"\n========================================================================================\n";
-
-const CHECK_EXERCISES_UNSOLVED_ERR: &str = "At least one exercise is already solved or failed to run. See the output above.
-If this is an intro exercise that is intended to be already solved, add `skip_check_unsolved = true` to the exercise's metadata in the `info.toml` file.";
+const SKIP_CHECK_UNSOLVED_HINT: &str = "If this is an introduction exercise that is intended to be already solved, add `skip_check_unsolved = true` to the exercise's metadata in the `info.toml` file";

src/dev/new.rs

@@ -76,8 +76,8 @@ pub fn new(path: &Path, no_git: bool) -> Result<()> {
 
 pub const GITIGNORE: &[u8] = b".rustlings-state.txt
 Cargo.lock
-target
-.vscode
+target/
+.vscode/
 !.vscode/extensions.json
 ";
 

src/dev/update.rs

@@ -4,18 +4,19 @@ use std::fs;
 use crate::{
     cargo_toml::updated_cargo_toml,
     info_file::{ExerciseInfo, InfoFile},
-    DEBUG_PROFILE,
 };
 
 // Update the `Cargo.toml` file.
 fn update_cargo_toml(
     exercise_infos: &[ExerciseInfo],
-    current_cargo_toml: &str,
-    exercise_path_prefix: &[u8],
     cargo_toml_path: &str,
+    exercise_path_prefix: &[u8],
 ) -> Result<()> {
+    let current_cargo_toml = fs::read_to_string(cargo_toml_path)
+        .with_context(|| format!("Failed to read the file `{cargo_toml_path}`"))?;
+
     let updated_cargo_toml =
-        updated_cargo_toml(exercise_infos, current_cargo_toml, exercise_path_prefix)?;
+        updated_cargo_toml(exercise_infos, &current_cargo_toml, exercise_path_prefix)?;
 
     fs::write(cargo_toml_path, updated_cargo_toml)
         .context("Failed to write the `Cargo.toml` file")?;
@@ -26,21 +27,14 @@ fn update_cargo_toml(
 pub fn update() -> Result<()> {
     let info_file = InfoFile::parse()?;
 
-    // A hack to make `cargo run -- dev update` work when developing Rustlings.
-    if DEBUG_PROFILE {
-        update_cargo_toml(
-            &info_file.exercises,
-            include_str!("../../dev-Cargo.toml"),
-            b"../",
-            "dev/Cargo.toml",
-        )
-        .context("Failed to update the file `dev/Cargo.toml`")?;
+    if cfg!(debug_assertions) {
+        // A hack to make `cargo run -- dev update` work when developing Rustlings.
+        update_cargo_toml(&info_file.exercises, "dev/Cargo.toml", b"../")
+            .context("Failed to update the file `dev/Cargo.toml`")?;
 
         println!("Updated `dev/Cargo.toml`");
     } else {
-        let current_cargo_toml =
-            fs::read_to_string("Cargo.toml").context("Failed to read the file `Cargo.toml`")?;
-        update_cargo_toml(&info_file.exercises, &current_cargo_toml, b"", "Cargo.toml")
+        update_cargo_toml(&info_file.exercises, "Cargo.toml", &[])
             .context("Failed to update the file `Cargo.toml`")?;
 
         println!("Updated `Cargo.toml`");

src/exercise.rs

@@ -1,46 +1,54 @@
 use anyhow::Result;
-use crossterm::style::{style, StyledContent, Stylize};
-use std::{
-    fmt::{self, Display, Formatter},
-    io::Write,
-    path::{Path, PathBuf},
-    process::Command,
+use crossterm::{
+    style::{Attribute, Color, ResetColor, SetAttribute, SetForegroundColor},
+    QueueableCommand,
 };
+use std::io::{self, StdoutLock, Write};
 
 use crate::{
-    cmd::{run_cmd, CargoCmd},
-    in_official_repo,
-    terminal_link::TerminalFileLink,
-    DEBUG_PROFILE,
+    cmd::CmdRunner,
+    term::{terminal_file_link, write_ansi},
 };
 
 /// The initial capacity of the output buffer.
 pub const OUTPUT_CAPACITY: usize = 1 << 14;
 
+pub fn solution_link_line(stdout: &mut StdoutLock, solution_path: &str) -> io::Result<()> {
+    stdout.queue(SetAttribute(Attribute::Bold))?;
+    stdout.write_all(b"Solution")?;
+    stdout.queue(ResetColor)?;
+    stdout.write_all(b" for comparison: ")?;
+    terminal_file_link(stdout, solution_path, Color::Cyan)?;
+    stdout.write_all(b"\n")
+}
+
 // Run an exercise binary and append its output to the `output` buffer.
 // Compilation must be done before calling this method.
-fn run_bin(bin_name: &str, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
-    writeln!(output, "{}", "Output".underlined())?;
+fn run_bin(
+    bin_name: &str,
+    mut output: Option<&mut Vec<u8>>,
+    cmd_runner: &CmdRunner,
+) -> Result<bool> {
+    if let Some(output) = output.as_deref_mut() {
+        write_ansi(output, SetAttribute(Attribute::Underlined));
+        output.extend_from_slice(b"Output");
+        write_ansi(output, ResetColor);
+        output.push(b'\n');
+    }
 
-    // 7 = "/debug/".len()
-    let mut bin_path = PathBuf::with_capacity(target_dir.as_os_str().len() + 7 + bin_name.len());
-    bin_path.push(target_dir);
-    bin_path.push("debug");
-    bin_path.push(bin_name);
+    let success = cmd_runner.run_debug_bin(bin_name, output.as_deref_mut())?;
 
-    let success = run_cmd(Command::new(&bin_path), &bin_path.to_string_lossy(), output)?;
-
-    if !success {
-        // This output is important to show the user that something went wrong.
-        // Otherwise, calling something like `exit(1)` in an exercise without further output
-        // leaves the user confused about why the exercise isn't done yet.
-        writeln!(
-            output,
-            "{}",
-            "The exercise didn't run successfully (nonzero exit code)"
-                .bold()
-                .red(),
-        )?;
+    if let Some(output) = output {
+        if !success {
+            // This output is important to show the user that something went wrong.
+            // Otherwise, calling something like `exit(1)` in an exercise without further output
+            // leaves the user confused about why the exercise isn't done yet.
+            write_ansi(output, SetAttribute(Attribute::Bold));
+            write_ansi(output, SetForegroundColor(Color::Red));
+            output.extend_from_slice(b"The exercise didn't run successfully (nonzero exit code)");
+            write_ansi(output, ResetColor);
+            output.push(b'\n');
+        }
     }
 
     Ok(success)
@@ -54,112 +62,114 @@ pub struct Exercise {
     pub path: &'static str,
     pub test: bool,
     pub strict_clippy: bool,
-    pub hint: String,
+    pub hint: &'static str,
     pub done: bool,
 }
 
-impl Exercise {
-    pub fn terminal_link(&self) -> StyledContent<TerminalFileLink<'_>> {
-        style(TerminalFileLink(self.path)).underlined().blue()
-    }
-}
-
-impl Display for Exercise {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        self.path.fmt(f)
-    }
-}
-
 pub trait RunnableExercise {
     fn name(&self) -> &str;
+    fn dir(&self) -> Option<&str>;
     fn strict_clippy(&self) -> bool;
     fn test(&self) -> bool;
 
     // Compile, check and run the exercise or its solution (depending on `bin_name´).
     // The output is written to the `output` buffer after clearing it.
-    fn run(&self, bin_name: &str, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
-        output.clear();
-
-        // Developing the official Rustlings.
-        let dev = DEBUG_PROFILE && in_official_repo();
-
-        let build_success = CargoCmd {
-            subcommand: "build",
-            args: &[],
-            bin_name,
-            description: "cargo build …",
-            hide_warnings: false,
-            target_dir,
-            output,
-            dev,
+    fn run<const FORCE_STRICT_CLIPPY: bool>(
+        &self,
+        bin_name: &str,
+        mut output: Option<&mut Vec<u8>>,
+        cmd_runner: &CmdRunner,
+    ) -> Result<bool> {
+        if let Some(output) = output.as_deref_mut() {
+            output.clear();
         }
-        .run()?;
+
+        let build_success = cmd_runner
+            .cargo("build", bin_name, output.as_deref_mut())
+            .run("cargo build …")?;
         if !build_success {
             return Ok(false);
         }
 
-        // Discard the output of `cargo build` because it will be shown again by Clippy.
-        output.clear();
+        // Discard the compiler output because it will be shown again by `cargo test` or Clippy.
+        if let Some(output) = output.as_deref_mut() {
+            output.clear();
+        }
+
+        if self.test() {
+            let output_is_some = output.is_some();
+            let mut test_cmd = cmd_runner.cargo("test", bin_name, output.as_deref_mut());
+            if output_is_some {
+                test_cmd.args(["--", "--color", "always", "--format", "pretty"]);
+            }
+            let test_success = test_cmd.run("cargo test …")?;
+            if !test_success {
+                run_bin(bin_name, output, cmd_runner)?;
+                return Ok(false);
+            }
+
+            // Discard the compiler output because it will be shown again by Clippy.
+            if let Some(output) = output.as_deref_mut() {
+                output.clear();
+            }
+        }
+
+        let mut clippy_cmd = cmd_runner.cargo("clippy", bin_name, output.as_deref_mut());
 
         // `--profile test` is required to also check code with `[cfg(test)]`.
-        let clippy_args: &[&str] = if self.strict_clippy() {
-            &["--profile", "test", "--", "-D", "warnings"]
+        if FORCE_STRICT_CLIPPY || self.strict_clippy() {
+            clippy_cmd.args(["--profile", "test", "--", "-D", "warnings"]);
         } else {
-            &["--profile", "test"]
-        };
-        let clippy_success = CargoCmd {
-            subcommand: "clippy",
-            args: clippy_args,
-            bin_name,
-            description: "cargo clippy …",
-            hide_warnings: false,
-            target_dir,
-            output,
-            dev,
-        }
-        .run()?;
-        if !clippy_success {
-            return Ok(false);
+            clippy_cmd.args(["--profile", "test"]);
         }
 
-        if !self.test() {
-            return run_bin(bin_name, output, target_dir);
-        }
+        let clippy_success = clippy_cmd.run("cargo clippy …")?;
+        let run_success = run_bin(bin_name, output, cmd_runner)?;
 
-        let test_success = CargoCmd {
-            subcommand: "test",
-            args: &["--", "--color", "always", "--show-output"],
-            bin_name,
-            description: "cargo test …",
-            // Hide warnings because they are shown by Clippy.
-            hide_warnings: true,
-            target_dir,
-            output,
-            dev,
-        }
-        .run()?;
-
-        let run_success = run_bin(bin_name, output, target_dir)?;
-
-        Ok(test_success && run_success)
+        Ok(clippy_success && run_success)
     }
 
     /// Compile, check and run the exercise.
     /// The output is written to the `output` buffer after clearing it.
     #[inline]
-    fn run_exercise(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
-        self.run(self.name(), output, target_dir)
+    fn run_exercise(&self, output: Option<&mut Vec<u8>>, cmd_runner: &CmdRunner) -> Result<bool> {
+        self.run::<false>(self.name(), output, cmd_runner)
     }
 
     /// Compile, check and run the exercise's solution.
     /// The output is written to the `output` buffer after clearing it.
-    fn run_solution(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
+    fn run_solution(&self, output: Option<&mut Vec<u8>>, cmd_runner: &CmdRunner) -> Result<bool> {
         let name = self.name();
-        let mut bin_name = String::with_capacity(name.len());
+        let mut bin_name = String::with_capacity(name.len() + 4);
         bin_name.push_str(name);
         bin_name.push_str("_sol");
 
-        self.run(&bin_name, output, target_dir)
+        self.run::<true>(&bin_name, output, cmd_runner)
+    }
+
+    fn sol_path(&self) -> String {
+        let name = self.name();
+
+        let mut path = if let Some(dir) = self.dir() {
+            // 14 = 10 + 1 + 3
+            // solutions/ + / + .rs
+            let mut path = String::with_capacity(14 + dir.len() + name.len());
+            path.push_str("solutions/");
+            path.push_str(dir);
+            path.push('/');
+            path
+        } else {
+            // 13 = 10 + 3
+            // solutions/ + .rs
+            let mut path = String::with_capacity(13 + name.len());
+            path.push_str("solutions/");
+            path
+        };
+
+        path.push_str(name);
+        path.push_str(".rs");
+
+        path
     }
 }
 
@@ -169,6 +179,11 @@ impl RunnableExercise for Exercise {
         self.name
     }
 
+    #[inline]
+    fn dir(&self) -> Option<&str> {
+        self.dir
+    }
+
     #[inline]
     fn strict_clippy(&self) -> bool {
         self.strict_clippy

src/info_file.rs

@@ -52,30 +52,6 @@ impl ExerciseInfo {
 
         path
     }
-
-    /// Path to the solution file starting with the `solutions/` directory.
-    pub fn sol_path(&self) -> String {
-        let mut path = if let Some(dir) = &self.dir {
-            // 14 = 10 + 1 + 3
-            // solutions/ + / + .rs
-            let mut path = String::with_capacity(14 + dir.len() + self.name.len());
-            path.push_str("solutions/");
-            path.push_str(dir);
-            path.push('/');
-            path
-        } else {
-            // 13 = 10 + 3
-            // solutions/ + .rs
-            let mut path = String::with_capacity(13 + self.name.len());
-            path.push_str("solutions/");
-            path
-        };
-
-        path.push_str(&self.name);
-        path.push_str(".rs");
-
-        path
-    }
 }
 
 impl RunnableExercise for ExerciseInfo {
@@ -84,6 +60,11 @@ impl RunnableExercise for ExerciseInfo {
         &self.name
     }
 
+    #[inline]
+    fn dir(&self) -> Option<&str> {
+        self.dir.as_deref()
+    }
+
     #[inline]
     fn strict_clippy(&self) -> bool {
         self.strict_clippy
@@ -135,4 +116,4 @@ impl InfoFile {
 }
 
 const NO_EXERCISES_ERR: &str = "There are no exercises yet!
-If you are developing third-party exercises, add at least one exercise before testing.";
+Add at least one exercise before testing.";

src/init.rs

@@ -1,32 +1,94 @@
 use anyhow::{bail, Context, Result};
-use crossterm::style::Stylize;
+use crossterm::{
+    style::{Attribute, Color, ResetColor, SetAttribute, SetForegroundColor},
+    QueueableCommand,
+};
+use serde::Deserialize;
 use std::{
     env::set_current_dir,
     fs::{self, create_dir},
-    io::ErrorKind,
-    path::Path,
+    io::{self, Write},
+    path::{Path, PathBuf},
     process::{Command, Stdio},
 };
 
-use crate::{cargo_toml::updated_cargo_toml, embedded::EMBEDDED_FILES, info_file::InfoFile};
+use crate::{
+    cargo_toml::updated_cargo_toml, embedded::EMBEDDED_FILES, exercise::RunnableExercise,
+    info_file::InfoFile, term::press_enter_prompt,
+};
+
+#[derive(Deserialize)]
+struct CargoLocateProject {
+    root: PathBuf,
+}
 
 pub fn init() -> Result<()> {
-    // Prevent initialization in a directory that contains the file `Cargo.toml`.
-    // This can mean that Rustlings was already initialized in this directory.
-    // Otherwise, this can cause problems with Cargo workspaces.
-    if Path::new("Cargo.toml").exists() {
-        bail!(CARGO_TOML_EXISTS_ERR);
+    let rustlings_dir = Path::new("rustlings");
+    if rustlings_dir.exists() {
+        bail!(RUSTLINGS_DIR_ALREADY_EXISTS_ERR);
     }
 
-    let rustlings_path = Path::new("rustlings");
-    if let Err(e) = create_dir(rustlings_path) {
-        if e.kind() == ErrorKind::AlreadyExists {
-            bail!(RUSTLINGS_DIR_ALREADY_EXISTS_ERR);
+    let locate_project_output = Command::new("cargo")
+        .arg("locate-project")
+        .arg("-q")
+        .arg("--workspace")
+        .stdin(Stdio::null())
+        .stderr(Stdio::null())
+        .output()
+        .context(CARGO_LOCATE_PROJECT_ERR)?;
+
+    let mut stdout = io::stdout().lock();
+    let mut init_git = true;
+
+    if locate_project_output.status.success() {
+        if Path::new("exercises").exists() && Path::new("solutions").exists() {
+            bail!(IN_INITIALIZED_DIR_ERR);
         }
-        return Err(e.into());
+
+        let workspace_manifest =
+            serde_json::de::from_slice::<CargoLocateProject>(&locate_project_output.stdout)
+                .context(
+                    "Failed to read the field `root` from the output of `cargo locate-project …`",
+                )?
+                .root;
+
+        let workspace_manifest_content = fs::read_to_string(&workspace_manifest)
+            .with_context(|| format!("Failed to read the file {}", workspace_manifest.display()))?;
+        if !workspace_manifest_content.contains("[workspace]\n")
+            && !workspace_manifest_content.contains("workspace.")
+        {
+            bail!("The current directory is already part of a Cargo project.\nPlease initialize Rustlings in a different directory");
+        }
+
+        stdout.write_all(b"This command will create the directory `rustlings/` as a member of this Cargo workspace.\nPress ENTER to continue ")?;
+        press_enter_prompt(&mut stdout)?;
+
+        // Make sure "rustlings" is added to `workspace.members` by making
+        // Cargo initialize a new project.
+        let status = Command::new("cargo")
+            .arg("new")
+            .arg("-q")
+            .arg("--vcs")
+            .arg("none")
+            .arg("rustlings")
+            .stdin(Stdio::null())
+            .stdout(Stdio::null())
+            .status()?;
+        if !status.success() {
+            bail!("Failed to initialize a new Cargo workspace member.\nPlease initialize Rustlings in a different directory");
+        }
+
+        stdout.write_all(b"The directory `rustlings` has been added to `workspace.members` in the `Cargo.toml` file of this Cargo workspace.\n")?;
+        fs::remove_dir_all("rustlings")
+            .context("Failed to remove the temporary directory `rustlings/`")?;
+        init_git = false;
+    } else {
+        stdout.write_all(b"This command will create the directory `rustlings/` which will contain the exercises.\nPress ENTER to continue ")?;
+        press_enter_prompt(&mut stdout)?;
     }
 
-    set_current_dir("rustlings")
+    create_dir(rustlings_dir).context("Failed to create the `rustlings/` directory")?;
+    set_current_dir(rustlings_dir)
         .context("Failed to change the current directory to `rustlings/`")?;
 
     let info_file = InfoFile::parse()?;
@@ -35,6 +97,11 @@ pub fn init() -> Result<()> {
         .context("Failed to initialize the `rustlings/exercises` directory")?;
 
     create_dir("solutions").context("Failed to create the `solutions/` directory")?;
+    fs::write(
+        "solutions/README.md",
+        include_bytes!("../solutions/README.md"),
+    )
+    .context("Failed to create the file rustlings/solutions/README.md")?;
     for dir in EMBEDDED_FILES.exercise_dirs {
         let mut dir_path = String::with_capacity(10 + dir.name.len());
         dir_path.push_str("solutions/");
@@ -70,41 +137,49 @@ pub fn init() -> Result<()> {
     fs::write(".vscode/extensions.json", VS_CODE_EXTENSIONS_JSON)
         .context("Failed to create the file `rustlings/.vscode/extensions.json`")?;
 
-    // Ignore any Git error because Git initialization is not required.
-    let _ = Command::new("git")
-        .arg("init")
-        .stdin(Stdio::null())
-        .stderr(Stdio::null())
-        .status();
+    if init_git {
+        // Ignore any Git error because Git initialization is not required.
+        let _ = Command::new("git")
+            .arg("init")
+            .stdin(Stdio::null())
+            .stdout(Stdio::null())
+            .stderr(Stdio::null())
+            .status();
+    }
 
-    println!(
-        "\n{}\n\n{}",
-        "Initialization done ✓".green(),
-        POST_INIT_MSG.bold(),
-    );
+    stdout.queue(SetForegroundColor(Color::Green))?;
+    stdout.write_all("Initialization done ✓".as_bytes())?;
+    stdout.queue(ResetColor)?;
+    stdout.write_all(b"\n\n")?;
+
+    stdout.queue(SetAttribute(Attribute::Bold))?;
+    stdout.write_all(POST_INIT_MSG)?;
+    stdout.queue(ResetColor)?;
 
     Ok(())
 }
 
+const CARGO_LOCATE_PROJECT_ERR: &str = "Failed to run the command `cargo locate-project …`
+Did you already install Rust?
+Try running `cargo --version` to diagnose the problem.";
+
 const INIT_SOLUTION_FILE: &[u8] = b"fn main() {
     // DON'T EDIT THIS SOLUTION FILE!
     // It will be automatically filled after you finish the exercise.
 }
 ";
 
-const GITIGNORE: &[u8] = b".rustlings-state.txt
-solutions
-Cargo.lock
-target
-.vscode
+const GITIGNORE: &[u8] = b"Cargo.lock
+target/
+.vscode/
 ";
 
 pub const VS_CODE_EXTENSIONS_JSON: &[u8] = br#"{"recommendations":["rust-lang.rust-analyzer"]}"#;
 
-const CARGO_TOML_EXISTS_ERR: &str = "The current directory contains the file `Cargo.toml`.
+const IN_INITIALIZED_DIR_ERR: &str = "It looks like Rustlings is already initialized in this directory.
 
 If you already initialized Rustlings, run the command `rustlings` for instructions on getting started with the exercises.
-Otherwise, please run `rustlings init` again in another directory.";
+Otherwise, please run `rustlings init` again in a different directory.";
 
 const RUSTLINGS_DIR_ALREADY_EXISTS_ERR: &str =
     "A directory with the name `rustlings` already exists in the current directory.
@@ -112,5 +187,6 @@ You probably already initialized Rustlings.
 Run `cd rustlings`
 Then run `rustlings` again";
 
-const POST_INIT_MSG: &str = "Run `cd rustlings` to go into the generated directory.
-Then run `rustlings` to get started.";
+const POST_INIT_MSG: &[u8] = b"Run `cd rustlings` to go into the generated directory.
+Then run `rustlings` to get started.
+";

src/list.rs

@@ -1,90 +1,109 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use crossterm::{
-    event::{self, Event, KeyCode, KeyEventKind},
-    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
-    ExecutableCommand,
+    cursor,
+    event::{
+        self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode, KeyEventKind, MouseEventKind,
+    },
+    terminal::{
+        disable_raw_mode, enable_raw_mode, DisableLineWrap, EnableLineWrap, EnterAlternateScreen,
+        LeaveAlternateScreen,
+    },
+    QueueableCommand,
 };
-use ratatui::{backend::CrosstermBackend, Terminal};
-use std::io;
+use std::io::{self, StdoutLock, Write};
 
 use crate::app_state::AppState;
 
-use self::state::{Filter, UiState};
+use self::state::{Filter, ListState};
 
+mod scroll_state;
 mod state;
 
+fn handle_list(app_state: &mut AppState, stdout: &mut StdoutLock) -> Result<()> {
+    let mut list_state = ListState::new(app_state, stdout)?;
+
+    loop {
+        match event::read().context("Failed to read terminal event")? {
+            Event::Key(key) => {
+                match key.kind {
+                    KeyEventKind::Release => continue,
+                    KeyEventKind::Press | KeyEventKind::Repeat => (),
+                }
+
+                list_state.message.clear();
+
+                match key.code {
+                    KeyCode::Char('q') => return Ok(()),
+                    KeyCode::Down | KeyCode::Char('j') => list_state.select_next(),
+                    KeyCode::Up | KeyCode::Char('k') => list_state.select_previous(),
+                    KeyCode::Home | KeyCode::Char('g') => list_state.select_first(),
+                    KeyCode::End | KeyCode::Char('G') => list_state.select_last(),
+                    KeyCode::Char('d') => {
+                        if list_state.filter() == Filter::Done {
+                            list_state.set_filter(Filter::None);
+                            list_state.message.push_str("Disabled filter DONE");
+                        } else {
+                            list_state.set_filter(Filter::Done);
+                            list_state.message.push_str(
+                                "Enabled filter DONE │ Press d again to disable the filter",
+                            );
+                        }
+                    }
+                    KeyCode::Char('p') => {
+                        let message = if list_state.filter() == Filter::Pending {
+                            list_state.set_filter(Filter::None);
+                            "Disabled filter PENDING"
+                        } else {
+                            list_state.set_filter(Filter::Pending);
+                            "Enabled filter PENDING │ Press p again to disable the filter"
+                        };
+
+                        list_state.message.push_str(message);
+                    }
+                    KeyCode::Char('r') => list_state.reset_selected()?,
+                    KeyCode::Char('c') => {
+                        if list_state.selected_to_current_exercise()? {
+                            return Ok(());
+                        }
+                    }
+                    // Redraw to remove the message.
+                    KeyCode::Esc => (),
+                    _ => continue,
+                }
+            }
+            Event::Mouse(event) => match event.kind {
+                MouseEventKind::ScrollDown => list_state.select_next(),
+                MouseEventKind::ScrollUp => list_state.select_previous(),
+                _ => continue,
+            },
+            Event::Resize(width, height) => list_state.set_term_size(width, height),
+            // Ignore
+            Event::FocusGained | Event::FocusLost => continue,
+        }
+
+        list_state.draw(stdout)?;
+    }
+}
+
 pub fn list(app_state: &mut AppState) -> Result<()> {
     let mut stdout = io::stdout().lock();
-    stdout.execute(EnterAlternateScreen)?;
+    stdout
+        .queue(EnterAlternateScreen)?
+        .queue(cursor::Hide)?
+        .queue(DisableLineWrap)?
+        .queue(EnableMouseCapture)?;
     enable_raw_mode()?;
 
-    let mut terminal = Terminal::new(CrosstermBackend::new(&mut stdout))?;
-    terminal.clear()?;
+    let res = handle_list(app_state, &mut stdout);
 
-    let mut ui_state = UiState::new(app_state);
-
-    'outer: loop {
-        terminal.draw(|frame| ui_state.draw(frame).unwrap())?;
-
-        let key = loop {
-            match event::read()? {
-                Event::Key(key) => match key.kind {
-                    KeyEventKind::Press | KeyEventKind::Repeat => break key,
-                    KeyEventKind::Release => (),
-                },
-                // Redraw
-                Event::Resize(_, _) => continue 'outer,
-                // Ignore
-                Event::FocusGained | Event::FocusLost | Event::Mouse(_) | Event::Paste(_) => (),
-            }
-        };
-
-        ui_state.message.clear();
-
-        match key.code {
-            KeyCode::Char('q') => break,
-            KeyCode::Down | KeyCode::Char('j') => ui_state.select_next(),
-            KeyCode::Up | KeyCode::Char('k') => ui_state.select_previous(),
-            KeyCode::Home | KeyCode::Char('g') => ui_state.select_first(),
-            KeyCode::End | KeyCode::Char('G') => ui_state.select_last(),
-            KeyCode::Char('d') => {
-                let message = if ui_state.filter == Filter::Done {
-                    ui_state.filter = Filter::None;
-                    "Disabled filter DONE"
-                } else {
-                    ui_state.filter = Filter::Done;
-                    "Enabled filter DONE │ Press d again to disable the filter"
-                };
-
-                ui_state = ui_state.with_updated_rows();
-                ui_state.message.push_str(message);
-            }
-            KeyCode::Char('p') => {
-                let message = if ui_state.filter == Filter::Pending {
-                    ui_state.filter = Filter::None;
-                    "Disabled filter PENDING"
-                } else {
-                    ui_state.filter = Filter::Pending;
-                    "Enabled filter PENDING │ Press p again to disable the filter"
-                };
-
-                ui_state = ui_state.with_updated_rows();
-                ui_state.message.push_str(message);
-            }
-            KeyCode::Char('r') => {
-                ui_state = ui_state.with_reset_selected()?;
-            }
-            KeyCode::Char('c') => {
-                ui_state.selected_to_current_exercise()?;
-                ui_state = ui_state.with_updated_rows();
-            }
-            _ => (),
-        }
-    }
-
-    drop(terminal);
-    stdout.execute(LeaveAlternateScreen)?;
+    // Restore the terminal even if we got an error.
+    stdout
+        .queue(LeaveAlternateScreen)?
+        .queue(cursor::Show)?
+        .queue(EnableLineWrap)?
+        .queue(DisableMouseCapture)?
+        .flush()?;
     disable_raw_mode()?;
 
-    Ok(())
+    res
 }

src/list/scroll_state.rs

@@ -0,0 +1,104 @@
+pub struct ScrollState {
+    n_rows: usize,
+    max_n_rows_to_display: usize,
+    selected: Option<usize>,
+    offset: usize,
+    scroll_padding: usize,
+    max_scroll_padding: usize,
+}
+
+impl ScrollState {
+    pub fn new(n_rows: usize, selected: Option<usize>, max_scroll_padding: usize) -> Self {
+        Self {
+            n_rows,
+            max_n_rows_to_display: 0,
+            selected,
+            offset: selected.map_or(0, |selected| selected.saturating_sub(max_scroll_padding)),
+            scroll_padding: 0,
+            max_scroll_padding,
+        }
+    }
+
+    #[inline]
+    pub fn offset(&self) -> usize {
+        self.offset
+    }
+
+    fn update_offset(&mut self) {
+        let Some(selected) = self.selected else {
+            return;
+        };
+
+        let min_offset = (selected + self.scroll_padding)
+            .saturating_sub(self.max_n_rows_to_display.saturating_sub(1));
+        let max_offset = selected.saturating_sub(self.scroll_padding);
+        let global_max_offset = self.n_rows.saturating_sub(self.max_n_rows_to_display);
+
+        self.offset = self
+            .offset
+            .max(min_offset)
+            .min(max_offset)
+            .min(global_max_offset);
+    }
+
+    #[inline]
+    pub fn selected(&self) -> Option<usize> {
+        self.selected
+    }
+
+    fn set_selected(&mut self, selected: usize) {
+        self.selected = Some(selected);
+        self.update_offset();
+    }
+
+    pub fn select_next(&mut self) {
+        if let Some(selected) = self.selected {
+            self.set_selected((selected + 1).min(self.n_rows - 1));
+        }
+    }
+
+    pub fn select_previous(&mut self) {
+        if let Some(selected) = self.selected {
+            self.set_selected(selected.saturating_sub(1));
+        }
+    }
+
+    pub fn select_first(&mut self) {
+        if self.n_rows > 0 {
+            self.set_selected(0);
+        }
+    }
+
+    pub fn select_last(&mut self) {
+        if self.n_rows > 0 {
+            self.set_selected(self.n_rows - 1);
+        }
+    }
+
+    pub fn set_n_rows(&mut self, n_rows: usize) {
+        self.n_rows = n_rows;
+
+        if self.n_rows == 0 {
+            self.selected = None;
+            return;
+        }
+
+        self.set_selected(self.selected.map_or(0, |selected| selected.min(n_rows - 1)));
+    }
+
+    #[inline]
+    fn update_scroll_padding(&mut self) {
+        self.scroll_padding = (self.max_n_rows_to_display / 4).min(self.max_scroll_padding);
+    }
+
+    #[inline]
+    pub fn max_n_rows_to_display(&self) -> usize {
+        self.max_n_rows_to_display
+    }
+
+    pub fn set_max_n_rows_to_display(&mut self, max_n_rows_to_display: usize) {
+        self.max_n_rows_to_display = max_n_rows_to_display;
+        self.update_scroll_padding();
+        self.update_offset();
+    }
+}

src/list/state.rs

@@ -1,14 +1,31 @@
 use anyhow::{Context, Result};
-use ratatui::{
-    layout::{Constraint, Rect},
-    style::{Style, Stylize},
-    text::{Line, Span},
-    widgets::{Block, Borders, HighlightSpacing, Paragraph, Row, Table, TableState},
-    Frame,
+use crossterm::{
+    cursor::{MoveTo, MoveToNextLine},
+    style::{Attribute, Color, ResetColor, SetAttribute, SetBackgroundColor, SetForegroundColor},
+    terminal::{self, BeginSynchronizedUpdate, Clear, ClearType, EndSynchronizedUpdate},
+    QueueableCommand,
+};
+use std::{
+    fmt::Write as _,
+    io::{self, StdoutLock, Write},
 };
-use std::fmt::Write;
 
-use crate::{app_state::AppState, progress_bar::progress_bar_ratatui};
+use crate::{
+    app_state::AppState,
+    exercise::Exercise,
+    term::{progress_bar, terminal_file_link, CountedWrite, MaxLenWriter},
+};
+
+use super::scroll_state::ScrollState;
+
+const COL_SPACING: usize = 2;
+
+fn next_ln(stdout: &mut StdoutLock) -> io::Result<()> {
+    stdout
+        .queue(Clear(ClearType::UntilNewLine))?
+        .queue(MoveToNextLine(1))?;
+    Ok(())
+}
 
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum Filter {
@@ -17,255 +34,352 @@ pub enum Filter {
     None,
 }
 
-pub struct UiState<'a> {
-    pub table: Table<'static>,
+pub struct ListState<'a> {
+    /// Footer message to be displayed if not empty.
     pub message: String,
-    pub filter: Filter,
     app_state: &'a mut AppState,
-    table_state: TableState,
-    n_rows: usize,
+    scroll_state: ScrollState,
+    name_col_padding: Vec<u8>,
+    filter: Filter,
+    term_width: u16,
+    term_height: u16,
+    separator_line: Vec<u8>,
+    narrow_term: bool,
+    show_footer: bool,
 }
 
-impl<'a> UiState<'a> {
-    pub fn with_updated_rows(mut self) -> Self {
-        let current_exercise_ind = self.app_state.current_exercise_ind();
+impl<'a> ListState<'a> {
+    pub fn new(app_state: &'a mut AppState, stdout: &mut StdoutLock) -> io::Result<Self> {
+        stdout.queue(Clear(ClearType::All))?;
 
-        self.n_rows = 0;
-        let rows = self
-            .app_state
-            .exercises()
-            .iter()
-            .enumerate()
-            .filter_map(|(ind, exercise)| {
-                let exercise_state = if exercise.done {
-                    if self.filter == Filter::Pending {
-                        return None;
-                    }
-
-                    "DONE".green()
-                } else {
-                    if self.filter == Filter::Done {
-                        return None;
-                    }
-
-                    "PENDING".yellow()
-                };
-
-                self.n_rows += 1;
-
-                let next = if ind == current_exercise_ind {
-                    ">>>>".bold().red()
-                } else {
-                    Span::default()
-                };
-
-                Some(Row::new([
-                    next,
-                    exercise_state,
-                    Span::raw(exercise.name),
-                    Span::raw(exercise.path),
-                ]))
-            });
-
-        self.table = self.table.rows(rows);
-
-        if self.n_rows == 0 {
-            self.table_state.select(None);
-        } else {
-            self.table_state.select(Some(
-                self.table_state
-                    .selected()
-                    .map_or(0, |selected| selected.min(self.n_rows - 1)),
-            ));
-        }
-
-        self
-    }
-
-    pub fn new(app_state: &'a mut AppState) -> Self {
-        let header = Row::new(["Next", "State", "Name", "Path"]);
-
-        let max_name_len = app_state
+        let name_col_title_len = 4;
+        let name_col_width = app_state
             .exercises()
             .iter()
             .map(|exercise| exercise.name.len())
             .max()
-            .unwrap_or(4) as u16;
-
-        let widths = [
-            Constraint::Length(4),
-            Constraint::Length(7),
-            Constraint::Length(max_name_len),
-            Constraint::Fill(1),
-        ];
-
-        let table = Table::default()
-            .widths(widths)
-            .header(header)
-            .column_spacing(2)
-            .highlight_spacing(HighlightSpacing::Always)
-            .highlight_style(Style::new().bg(ratatui::style::Color::Rgb(50, 50, 50)))
-            .highlight_symbol("🦀")
-            .block(Block::default().borders(Borders::BOTTOM));
-
-        let selected = app_state.current_exercise_ind();
-        let table_state = TableState::default()
-            .with_offset(selected.saturating_sub(10))
-            .with_selected(Some(selected));
+            .map_or(name_col_title_len, |max| max.max(name_col_title_len));
+        let name_col_padding = vec![b' '; name_col_width + COL_SPACING];
 
         let filter = Filter::None;
-        let n_rows = app_state.exercises().len();
+        let n_rows_with_filter = app_state.exercises().len();
+        let selected = app_state.current_exercise_ind();
 
-        let slf = Self {
-            table,
+        let (width, height) = terminal::size()?;
+        let scroll_state = ScrollState::new(n_rows_with_filter, Some(selected), 5);
+
+        let mut slf = Self {
             message: String::with_capacity(128),
-            filter,
             app_state,
-            table_state,
-            n_rows,
+            scroll_state,
+            name_col_padding,
+            filter,
+            // Set by `set_term_size`
+            term_width: 0,
+            term_height: 0,
+            separator_line: Vec::new(),
+            narrow_term: false,
+            show_footer: true,
         };
 
-        slf.with_updated_rows()
+        slf.set_term_size(width, height);
+        slf.draw(stdout)?;
+
+        Ok(slf)
     }
 
-    pub fn select_next(&mut self) {
-        if self.n_rows > 0 {
-            let next = self
-                .table_state
-                .selected()
-                .map_or(0, |selected| (selected + 1).min(self.n_rows - 1));
-            self.table_state.select(Some(next));
+    pub fn set_term_size(&mut self, width: u16, height: u16) {
+        self.term_width = width;
+        self.term_height = height;
+
+        if height == 0 {
+            return;
         }
-    }
 
-    pub fn select_previous(&mut self) {
-        if self.n_rows > 0 {
-            let previous = self
-                .table_state
-                .selected()
-                .map_or(0, |selected| selected.saturating_sub(1));
-            self.table_state.select(Some(previous));
+        let wide_help_footer_width = 95;
+        // The help footer is shorter when nothing is selected.
+        self.narrow_term = width < wide_help_footer_width && self.scroll_state.selected().is_some();
+
+        let header_height = 1;
+        // 2 separator, 1 progress bar, 1-2 footer message.
+        let footer_height = 4 + u16::from(self.narrow_term);
+        self.show_footer = height > header_height + footer_height;
+
+        if self.show_footer {
+            self.separator_line = "─".as_bytes().repeat(width as usize);
         }
-    }
 
-    pub fn select_first(&mut self) {
-        if self.n_rows > 0 {
-            self.table_state.select(Some(0));
-        }
-    }
-
-    pub fn select_last(&mut self) {
-        if self.n_rows > 0 {
-            self.table_state.select(Some(self.n_rows - 1));
-        }
-    }
-
-    pub fn draw(&mut self, frame: &mut Frame) -> Result<()> {
-        let area = frame.size();
-
-        frame.render_stateful_widget(
-            &self.table,
-            Rect {
-                x: 0,
-                y: 0,
-                width: area.width,
-                height: area.height - 3,
-            },
-            &mut self.table_state,
+        self.scroll_state.set_max_n_rows_to_display(
+            height.saturating_sub(header_height + u16::from(self.show_footer) * footer_height)
+                as usize,
         );
+    }
 
-        frame.render_widget(
-            Paragraph::new(progress_bar_ratatui(
+    fn draw_rows(
+        &self,
+        stdout: &mut StdoutLock,
+        filtered_exercises: impl Iterator<Item = (usize, &'a Exercise)>,
+    ) -> io::Result<usize> {
+        let current_exercise_ind = self.app_state.current_exercise_ind();
+        let row_offset = self.scroll_state.offset();
+        let mut n_displayed_rows = 0;
+
+        for (exercise_ind, exercise) in filtered_exercises
+            .skip(row_offset)
+            .take(self.scroll_state.max_n_rows_to_display())
+        {
+            let mut writer = MaxLenWriter::new(stdout, self.term_width as usize);
+
+            if self.scroll_state.selected() == Some(row_offset + n_displayed_rows) {
+                writer.stdout.queue(SetBackgroundColor(Color::Rgb {
+                    r: 40,
+                    g: 40,
+                    b: 40,
+                }))?;
+                // The crab emoji has the width of two ascii chars.
+                writer.add_to_len(2);
+                writer.stdout.write_all("🦀".as_bytes())?;
+            } else {
+                writer.write_ascii(b"  ")?;
+            }
+
+            if exercise_ind == current_exercise_ind {
+                writer.stdout.queue(SetForegroundColor(Color::Red))?;
+                writer.write_ascii(b">>>>>>>  ")?;
+            } else {
+                writer.write_ascii(b"         ")?;
+            }
+
+            if exercise.done {
+                writer.stdout.queue(SetForegroundColor(Color::Green))?;
+                writer.write_ascii(b"DONE     ")?;
+            } else {
+                writer.stdout.queue(SetForegroundColor(Color::Yellow))?;
+                writer.write_ascii(b"PENDING  ")?;
+            }
+
+            writer.stdout.queue(SetForegroundColor(Color::Reset))?;
+
+            writer.write_str(exercise.name)?;
+            writer.write_ascii(&self.name_col_padding[exercise.name.len()..])?;
+
+            // The list links aren't shown correctly in VS Code on Windows.
+            // But VS Code shows its own links anyway.
+            if self.app_state.vs_code() {
+                writer.write_str(exercise.path)?;
+            } else {
+                terminal_file_link(&mut writer, exercise.path, Color::Blue)?;
+            }
+
+            next_ln(stdout)?;
+            stdout.queue(ResetColor)?;
+            n_displayed_rows += 1;
+        }
+
+        Ok(n_displayed_rows)
+    }
+
+    pub fn draw(&mut self, stdout: &mut StdoutLock) -> io::Result<()> {
+        if self.term_height == 0 {
+            return Ok(());
+        }
+
+        stdout.queue(BeginSynchronizedUpdate)?.queue(MoveTo(0, 0))?;
+
+        // Header
+        let mut writer = MaxLenWriter::new(stdout, self.term_width as usize);
+        writer.write_ascii(b"  Current  State    Name")?;
+        writer.write_ascii(&self.name_col_padding[4..])?;
+        writer.write_ascii(b"Path")?;
+        next_ln(stdout)?;
+
+        // Rows
+        let iter = self.app_state.exercises().iter().enumerate();
+        let n_displayed_rows = match self.filter {
+            Filter::Done => self.draw_rows(stdout, iter.filter(|(_, exercise)| exercise.done))?,
+            Filter::Pending => {
+                self.draw_rows(stdout, iter.filter(|(_, exercise)| !exercise.done))?
+            }
+            Filter::None => self.draw_rows(stdout, iter)?,
+        };
+
+        for _ in 0..self.scroll_state.max_n_rows_to_display() - n_displayed_rows {
+            next_ln(stdout)?;
+        }
+
+        if self.show_footer {
+            stdout.write_all(&self.separator_line)?;
+            next_ln(stdout)?;
+
+            progress_bar(
+                &mut MaxLenWriter::new(stdout, self.term_width as usize),
                 self.app_state.n_done(),
                 self.app_state.exercises().len() as u16,
-                area.width,
-            )?)
-            .block(Block::default().borders(Borders::BOTTOM)),
-            Rect {
-                x: 0,
-                y: area.height - 3,
-                width: area.width,
-                height: 2,
-            },
-        );
+                self.term_width,
+            )?;
+            next_ln(stdout)?;
 
-        let message = if self.message.is_empty() {
-            // Help footer.
-            let mut spans = Vec::with_capacity(4);
-            spans.push(Span::raw(
-                "↓/j ↑/k home/g end/G │ <c>ontinue at │ <r>eset │ filter ",
-            ));
-            match self.filter {
-                Filter::Done => {
-                    spans.push("<d>one".underlined().magenta());
-                    spans.push(Span::raw("/<p>ending"));
+            stdout.write_all(&self.separator_line)?;
+            next_ln(stdout)?;
+
+            let mut writer = MaxLenWriter::new(stdout, self.term_width as usize);
+            if self.message.is_empty() {
+                // Help footer message
+                if self.scroll_state.selected().is_some() {
+                    writer.write_str("↓/j ↑/k home/g end/G | <c>ontinue at | <r>eset exercise")?;
+                    if self.narrow_term {
+                        next_ln(stdout)?;
+                        writer = MaxLenWriter::new(stdout, self.term_width as usize);
+
+                        writer.write_ascii(b"filter ")?;
+                    } else {
+                        writer.write_ascii(b" | filter ")?;
+                    }
+                } else {
+                    // Nothing selected (and nothing shown), so only display filter and quit.
+                    writer.write_ascii(b"filter ")?;
                 }
-                Filter::Pending => {
-                    spans.push(Span::raw("<d>one/"));
-                    spans.push("<p>ending".underlined().magenta());
+
+                match self.filter {
+                    Filter::Done => {
+                        writer
+                            .stdout
+                            .queue(SetForegroundColor(Color::Magenta))?
+                            .queue(SetAttribute(Attribute::Underlined))?;
+                        writer.write_ascii(b"<d>one")?;
+                        writer.stdout.queue(ResetColor)?;
+                        writer.write_ascii(b"/<p>ending")?;
+                    }
+                    Filter::Pending => {
+                        writer.write_ascii(b"<d>one/")?;
+                        writer
+                            .stdout
+                            .queue(SetForegroundColor(Color::Magenta))?
+                            .queue(SetAttribute(Attribute::Underlined))?;
+                        writer.write_ascii(b"<p>ending")?;
+                        writer.stdout.queue(ResetColor)?;
+                    }
+                    Filter::None => writer.write_ascii(b"<d>one/<p>ending")?,
+                }
+
+                writer.write_ascii(b" | <q>uit list")?;
+                next_ln(stdout)?;
+            } else {
+                writer.stdout.queue(SetForegroundColor(Color::Magenta))?;
+                writer.write_str(&self.message)?;
+                stdout.queue(ResetColor)?;
+                next_ln(stdout)?;
+
+                if self.narrow_term {
+                    next_ln(stdout)?;
                 }
-                Filter::None => spans.push(Span::raw("<d>one/<p>ending")),
             }
-            spans.push(Span::raw(" │ <q>uit"));
-            Line::from(spans)
-        } else {
-            Line::from(self.message.as_str().light_blue())
+        }
+
+        stdout.queue(EndSynchronizedUpdate)?.flush()
+    }
+
+    fn update_rows(&mut self) {
+        let n_rows = match self.filter {
+            Filter::Done => self
+                .app_state
+                .exercises()
+                .iter()
+                .filter(|exercise| exercise.done)
+                .count(),
+            Filter::Pending => self
+                .app_state
+                .exercises()
+                .iter()
+                .filter(|exercise| !exercise.done)
+                .count(),
+            Filter::None => self.app_state.exercises().len(),
         };
-        frame.render_widget(
-            message,
-            Rect {
-                x: 0,
-                y: area.height - 1,
-                width: area.width,
-                height: 1,
-            },
-        );
+
+        self.scroll_state.set_n_rows(n_rows);
+    }
+
+    #[inline]
+    pub fn filter(&self) -> Filter {
+        self.filter
+    }
+
+    pub fn set_filter(&mut self, filter: Filter) {
+        self.filter = filter;
+        self.update_rows();
+    }
+
+    #[inline]
+    pub fn select_next(&mut self) {
+        self.scroll_state.select_next();
+    }
+
+    #[inline]
+    pub fn select_previous(&mut self) {
+        self.scroll_state.select_previous();
+    }
+
+    #[inline]
+    pub fn select_first(&mut self) {
+        self.scroll_state.select_first();
+    }
+
+    #[inline]
+    pub fn select_last(&mut self) {
+        self.scroll_state.select_last();
+    }
+
+    fn selected_to_exercise_ind(&self, selected: usize) -> Result<usize> {
+        match self.filter {
+            Filter::Done => self
+                .app_state
+                .exercises()
+                .iter()
+                .enumerate()
+                .filter(|(_, exercise)| exercise.done)
+                .nth(selected)
+                .context("Invalid selection index")
+                .map(|(ind, _)| ind),
+            Filter::Pending => self
+                .app_state
+                .exercises()
+                .iter()
+                .enumerate()
+                .filter(|(_, exercise)| !exercise.done)
+                .nth(selected)
+                .context("Invalid selection index")
+                .map(|(ind, _)| ind),
+            Filter::None => Ok(selected),
+        }
+    }
+
+    pub fn reset_selected(&mut self) -> Result<()> {
+        let Some(selected) = self.scroll_state.selected() else {
+            self.message.push_str("Nothing selected to reset!");
+            return Ok(());
+        };
+
+        let exercise_ind = self.selected_to_exercise_ind(selected)?;
+        let exercise_name = self.app_state.reset_exercise_by_ind(exercise_ind)?;
+        self.update_rows();
+        write!(
+            self.message,
+            "The exercise `{exercise_name}` has been reset",
+        )?;
 
         Ok(())
     }
 
-    pub fn with_reset_selected(mut self) -> Result<Self> {
-        let Some(selected) = self.table_state.selected() else {
-            return Ok(self);
+    // Return `true` if there was something to select.
+    pub fn selected_to_current_exercise(&mut self) -> Result<bool> {
+        let Some(selected) = self.scroll_state.selected() else {
+            self.message.push_str("Nothing selected to continue at!");
+            return Ok(false);
         };
 
-        let ind = self
-            .app_state
-            .exercises()
-            .iter()
-            .enumerate()
-            .filter_map(|(ind, exercise)| match self.filter {
-                Filter::Done => exercise.done.then_some(ind),
-                Filter::Pending => (!exercise.done).then_some(ind),
-                Filter::None => Some(ind),
-            })
-            .nth(selected)
-            .context("Invalid selection index")?;
+        let exercise_ind = self.selected_to_exercise_ind(selected)?;
+        self.app_state.set_current_exercise_ind(exercise_ind)?;
 
-        let exercise_path = self.app_state.reset_exercise_by_ind(ind)?;
-        write!(self.message, "The exercise {exercise_path} has been reset")?;
-
-        Ok(self.with_updated_rows())
-    }
-
-    pub fn selected_to_current_exercise(&mut self) -> Result<()> {
-        let Some(selected) = self.table_state.selected() else {
-            return Ok(());
-        };
-
-        let ind = self
-            .app_state
-            .exercises()
-            .iter()
-            .enumerate()
-            .filter_map(|(ind, exercise)| match self.filter {
-                Filter::Done => exercise.done.then_some(ind),
-                Filter::Pending => (!exercise.done).then_some(ind),
-                Filter::None => Some(ind),
-            })
-            .nth(selected)
-            .context("Invalid selection index")?;
-
-        self.app_state.set_current_exercise_ind(ind)
+        Ok(true)
     }
 }

src/main.rs

@@ -2,53 +2,29 @@ use anyhow::{bail, Context, Result};
 use app_state::StateFileStatus;
 use clap::{Parser, Subcommand};
 use std::{
-    io::{self, BufRead, IsTerminal, StdoutLock, Write},
+    io::{self, IsTerminal, Write},
     path::Path,
     process::exit,
 };
+use term::{clear_terminal, press_enter_prompt};
 
 use self::{app_state::AppState, dev::DevCommands, info_file::InfoFile, watch::WatchExit};
 
 mod app_state;
 mod cargo_toml;
 mod cmd;
+mod collections;
 mod dev;
 mod embedded;
 mod exercise;
 mod info_file;
 mod init;
 mod list;
-mod progress_bar;
 mod run;
-mod terminal_link;
+mod term;
 mod watch;
 
 const CURRENT_FORMAT_VERSION: u8 = 1;
-const DEBUG_PROFILE: bool = {
-    #[allow(unused_assignments, unused_mut)]
-    let mut debug_profile = false;
-
-    #[cfg(debug_assertions)]
-    {
-        debug_profile = true;
-    }
-
-    debug_profile
-};
-
-// The current directory is the official Rustligns repository.
-fn in_official_repo() -> bool {
-    Path::new("dev/rustlings-repo.txt").exists()
-}
-
-fn clear_terminal(stdout: &mut StdoutLock) -> io::Result<()> {
-    stdout.write_all(b"\x1b[H\x1b[2J\x1b[3J")
-}
-
-fn press_enter_prompt() -> io::Result<()> {
-    io::stdin().lock().read_until(b'\n', &mut Vec::new())?;
-    Ok(())
-}
 
 /// Rustlings is a collection of small exercises to get you used to writing and reading Rust code
 #[derive(Parser)]
@@ -89,26 +65,12 @@ enum Subcommands {
 fn main() -> Result<()> {
     let args = Args::parse();
 
-    if !DEBUG_PROFILE && in_official_repo() {
+    if cfg!(not(debug_assertions)) && Path::new("dev/rustlings-repo.txt").exists() {
         bail!("{OLD_METHOD_ERR}");
     }
 
     match args.command {
-        Some(Subcommands::Init) => {
-            if DEBUG_PROFILE {
-                bail!("Disabled in the debug build");
-            }
-
-            {
-                let mut stdout = io::stdout().lock();
-                stdout.write_all(b"This command will create the directory `rustlings/` which will contain the exercises.\nPress ENTER to continue ")?;
-                stdout.flush()?;
-                press_enter_prompt()?;
-                stdout.write_all(b"\n")?;
-            }
-
-            return init::init().context("Initialization failed");
-        }
+        Some(Subcommands::Init) => return init::init().context("Initialization failed"),
         Some(Subcommands::Dev(dev_command)) => return dev_command.run(),
         _ => (),
     }
@@ -136,11 +98,12 @@ fn main() -> Result<()> {
                 let mut stdout = io::stdout().lock();
                 clear_terminal(&mut stdout)?;
 
-                let welcome_message = welcome_message.trim();
+                let welcome_message = welcome_message.trim_ascii();
                 write!(stdout, "{welcome_message}\n\nPress ENTER to continue ")?;
-                stdout.flush()?;
-                press_enter_prompt()?;
+                press_enter_prompt(&mut stdout)?;
                 clear_terminal(&mut stdout)?;
+                // Flush to be able to show errors occurring before printing a newline to stdout.
+                stdout.flush()?;
             }
             StateFileStatus::Read => (),
         }

src/progress_bar.rs

@@ -1,100 +0,0 @@
-use anyhow::{bail, Result};
-use ratatui::text::{Line, Span};
-use std::fmt::Write;
-
-const PREFIX: &str = "Progress: [";
-const PREFIX_WIDTH: u16 = PREFIX.len() as u16;
-// Leaving the last char empty (_) for `total` > 99.
-const POSTFIX_WIDTH: u16 = "] xxx/xx exercises_".len() as u16;
-const WRAPPER_WIDTH: u16 = PREFIX_WIDTH + POSTFIX_WIDTH;
-const MIN_LINE_WIDTH: u16 = WRAPPER_WIDTH + 4;
-
-const PROGRESS_EXCEEDS_MAX_ERR: &str =
-    "The progress of the progress bar is higher than the maximum";
-
-/// Terminal progress bar to be used when not using Ratataui.
-pub fn progress_bar(progress: u16, total: u16, line_width: u16) -> Result<String> {
-    use crossterm::style::Stylize;
-
-    if progress > total {
-        bail!(PROGRESS_EXCEEDS_MAX_ERR);
-    }
-
-    if line_width < MIN_LINE_WIDTH {
-        return Ok(format!("Progress: {progress}/{total} exercises"));
-    }
-
-    let mut line = String::with_capacity(usize::from(line_width));
-    line.push_str(PREFIX);
-
-    let width = line_width - WRAPPER_WIDTH;
-    let filled = (width * progress) / total;
-
-    let mut green_part = String::with_capacity(usize::from(filled + 1));
-    for _ in 0..filled {
-        green_part.push('#');
-    }
-
-    if filled < width {
-        green_part.push('>');
-    }
-    write!(line, "{}", green_part.green()).unwrap();
-
-    let width_minus_filled = width - filled;
-    if width_minus_filled > 1 {
-        let red_part_width = width_minus_filled - 1;
-        let mut red_part = String::with_capacity(usize::from(red_part_width));
-        for _ in 0..red_part_width {
-            red_part.push('-');
-        }
-        write!(line, "{}", red_part.red()).unwrap();
-    }
-
-    writeln!(line, "] {progress:>3}/{total} exercises").unwrap();
-
-    Ok(line)
-}
-
-/// Progress bar to be used with Ratataui.
-// Not using Ratatui's Gauge widget to keep the progress bar consistent.
-pub fn progress_bar_ratatui(progress: u16, total: u16, line_width: u16) -> Result<Line<'static>> {
-    use ratatui::style::Stylize;
-
-    if progress > total {
-        bail!(PROGRESS_EXCEEDS_MAX_ERR);
-    }
-
-    if line_width < MIN_LINE_WIDTH {
-        return Ok(Line::raw(format!("Progress: {progress}/{total} exercises")));
-    }
-
-    let mut spans = Vec::with_capacity(4);
-    spans.push(Span::raw(PREFIX));
-
-    let width = line_width - WRAPPER_WIDTH;
-    let filled = (width * progress) / total;
-
-    let mut green_part = String::with_capacity(usize::from(filled + 1));
-    for _ in 0..filled {
-        green_part.push('#');
-    }
-
-    if filled < width {
-        green_part.push('>');
-    }
-    spans.push(green_part.green());
-
-    let width_minus_filled = width - filled;
-    if width_minus_filled > 1 {
-        let red_part_width = width_minus_filled - 1;
-        let mut red_part = String::with_capacity(usize::from(red_part_width));
-        for _ in 0..red_part_width {
-            red_part.push('-');
-        }
-        spans.push(red_part.red());
-    }
-
-    spans.push(Span::raw(format!("] {progress:>3}/{total} exercises")));
-
-    Ok(Line::from(spans))
-}

src/run.rs

@@ -1,17 +1,23 @@
-use anyhow::{bail, Result};
-use crossterm::style::{style, Stylize};
-use std::io::{self, Write};
+use anyhow::Result;
+use crossterm::{
+    style::{Color, ResetColor, SetForegroundColor},
+    QueueableCommand,
+};
+use std::{
+    io::{self, Write},
+    process::exit,
+};
 
 use crate::{
     app_state::{AppState, ExercisesProgress},
-    exercise::{RunnableExercise, OUTPUT_CAPACITY},
-    terminal_link::TerminalFileLink,
+    exercise::{solution_link_line, RunnableExercise, OUTPUT_CAPACITY},
+    term::terminal_file_link,
 };
 
 pub fn run(app_state: &mut AppState) -> Result<()> {
     let exercise = app_state.current_exercise();
     let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-    let success = exercise.run_exercise(&mut output, app_state.target_dir())?;
+    let success = exercise.run_exercise(Some(&mut output), app_state.cmd_runner())?;
 
     let mut stdout = io::stdout().lock();
     stdout.write_all(&output)?;
@@ -19,32 +25,31 @@ pub fn run(app_state: &mut AppState) -> Result<()> {
     if !success {
         app_state.set_pending(app_state.current_exercise_ind())?;
 
-        bail!(
-            "Ran {} with errors",
-            app_state.current_exercise().terminal_link(),
-        );
+        stdout.write_all(b"Ran ")?;
+        terminal_file_link(&mut stdout, app_state.current_exercise().path, Color::Blue)?;
+        stdout.write_all(b" with errors\n")?;
+        exit(1);
     }
 
-    writeln!(
-        stdout,
-        "{}{}",
-        "✓ Successfully ran ".green(),
-        exercise.path.green(),
-    )?;
+    stdout.queue(SetForegroundColor(Color::Green))?;
+    stdout.write_all("✓ Successfully ran ".as_bytes())?;
+    stdout.write_all(exercise.path.as_bytes())?;
+    stdout.queue(ResetColor)?;
+    stdout.write_all(b"\n")?;
 
     if let Some(solution_path) = app_state.current_solution_path()? {
-        println!(
-            "\nA solution file can be found at {}\n",
-            style(TerminalFileLink(&solution_path)).underlined().green(),
-        );
+        stdout.write_all(b"\n")?;
+        solution_link_line(&mut stdout, &solution_path)?;
+        stdout.write_all(b"\n")?;
     }
 
     match app_state.done_current_exercise(&mut stdout)? {
+        ExercisesProgress::CurrentPending | ExercisesProgress::NewPending => {
+            stdout.write_all(b"Next exercise: ")?;
+            terminal_file_link(&mut stdout, app_state.current_exercise().path, Color::Blue)?;
+            stdout.write_all(b"\n")?;
+        }
         ExercisesProgress::AllDone => (),
-        ExercisesProgress::CurrentPending | ExercisesProgress::NewPending => println!(
-            "Next exercise: {}",
-            app_state.current_exercise().terminal_link(),
-        ),
     }
 
     Ok(())

src/term.rs

@@ -0,0 +1,202 @@
+use std::{
+    fmt, fs,
+    io::{self, BufRead, StdoutLock, Write},
+};
+
+use crossterm::{
+    cursor::MoveTo,
+    style::{Attribute, Color, ResetColor, SetAttribute, SetForegroundColor},
+    terminal::{Clear, ClearType},
+    Command, QueueableCommand,
+};
+
+pub struct MaxLenWriter<'a, 'b> {
+    pub stdout: &'a mut StdoutLock<'b>,
+    len: usize,
+    max_len: usize,
+}
+
+impl<'a, 'b> MaxLenWriter<'a, 'b> {
+    #[inline]
+    pub fn new(stdout: &'a mut StdoutLock<'b>, max_len: usize) -> Self {
+        Self {
+            stdout,
+            len: 0,
+            max_len,
+        }
+    }
+
+    // Additional is for emojis that take more space.
+    #[inline]
+    pub fn add_to_len(&mut self, additional: usize) {
+        self.len += additional;
+    }
+}
+
+pub trait CountedWrite<'a> {
+    fn write_ascii(&mut self, ascii: &[u8]) -> io::Result<()>;
+    fn write_str(&mut self, unicode: &str) -> io::Result<()>;
+    fn stdout(&mut self) -> &mut StdoutLock<'a>;
+}
+
+impl<'a, 'b> CountedWrite<'b> for MaxLenWriter<'a, 'b> {
+    fn write_ascii(&mut self, ascii: &[u8]) -> io::Result<()> {
+        let n = ascii.len().min(self.max_len.saturating_sub(self.len));
+        if n > 0 {
+            self.stdout.write_all(&ascii[..n])?;
+            self.len += n;
+        }
+        Ok(())
+    }
+
+    fn write_str(&mut self, unicode: &str) -> io::Result<()> {
+        if let Some((ind, c)) = unicode
+            .char_indices()
+            .take(self.max_len.saturating_sub(self.len))
+            .last()
+        {
+            self.stdout
+                .write_all(&unicode.as_bytes()[..ind + c.len_utf8()])?;
+            self.len += ind + 1;
+        }
+
+        Ok(())
+    }
+
+    #[inline]
+    fn stdout(&mut self) -> &mut StdoutLock<'b> {
+        self.stdout
+    }
+}
+
+impl<'a> CountedWrite<'a> for StdoutLock<'a> {
+    #[inline]
+    fn write_ascii(&mut self, ascii: &[u8]) -> io::Result<()> {
+        self.write_all(ascii)
+    }
+
+    #[inline]
+    fn write_str(&mut self, unicode: &str) -> io::Result<()> {
+        self.write_all(unicode.as_bytes())
+    }
+
+    #[inline]
+    fn stdout(&mut self) -> &mut StdoutLock<'a> {
+        self
+    }
+}
+
+/// Terminal progress bar to be used when not using Ratataui.
+pub fn progress_bar<'a>(
+    writer: &mut impl CountedWrite<'a>,
+    progress: u16,
+    total: u16,
+    line_width: u16,
+) -> io::Result<()> {
+    debug_assert!(progress <= total);
+
+    const PREFIX: &[u8] = b"Progress: [";
+    const PREFIX_WIDTH: u16 = PREFIX.len() as u16;
+    // Leaving the last char empty (_) for `total` > 99.
+    const POSTFIX_WIDTH: u16 = "] xxx/xx exercises_".len() as u16;
+    const WRAPPER_WIDTH: u16 = PREFIX_WIDTH + POSTFIX_WIDTH;
+    const MIN_LINE_WIDTH: u16 = WRAPPER_WIDTH + 4;
+
+    if line_width < MIN_LINE_WIDTH {
+        writer.write_ascii(b"Progress: ")?;
+        // Integers are in ASCII.
+        writer.write_ascii(format!("{progress}/{total}").as_bytes())?;
+        return writer.write_ascii(b" exercises");
+    }
+
+    let stdout = writer.stdout();
+    stdout.write_all(PREFIX)?;
+
+    let width = line_width - WRAPPER_WIDTH;
+    let filled = (width * progress) / total;
+
+    stdout.queue(SetForegroundColor(Color::Green))?;
+    for _ in 0..filled {
+        stdout.write_all(b"#")?;
+    }
+
+    if filled < width {
+        stdout.write_all(b">")?;
+    }
+
+    let width_minus_filled = width - filled;
+    if width_minus_filled > 1 {
+        let red_part_width = width_minus_filled - 1;
+        stdout.queue(SetForegroundColor(Color::Red))?;
+        for _ in 0..red_part_width {
+            stdout.write_all(b"-")?;
+        }
+    }
+
+    stdout.queue(ResetColor)?;
+    write!(stdout, "] {progress:>3}/{total} exercises")
+}
+
+pub fn clear_terminal(stdout: &mut StdoutLock) -> io::Result<()> {
+    stdout
+        .queue(MoveTo(0, 0))?
+        .queue(Clear(ClearType::All))?
+        .queue(Clear(ClearType::Purge))
+        .map(|_| ())
+}
+
+pub fn press_enter_prompt(stdout: &mut StdoutLock) -> io::Result<()> {
+    stdout.flush()?;
+    io::stdin().lock().read_until(b'\n', &mut Vec::new())?;
+    stdout.write_all(b"\n")
+}
+
+pub fn terminal_file_link<'a>(
+    writer: &mut impl CountedWrite<'a>,
+    path: &str,
+    color: Color,
+) -> io::Result<()> {
+    let canonical_path = fs::canonicalize(path).ok();
+
+    let Some(canonical_path) = canonical_path.as_deref().and_then(|p| p.to_str()) else {
+        return writer.write_str(path);
+    };
+
+    // Windows itself can't handle its verbatim paths.
+    #[cfg(windows)]
+    let canonical_path = if canonical_path.len() > 5 && &canonical_path[0..4] == r"\\?\" {
+        &canonical_path[4..]
+    } else {
+        canonical_path
+    };
+
+    writer
+        .stdout()
+        .queue(SetForegroundColor(color))?
+        .queue(SetAttribute(Attribute::Underlined))?;
+    writer.stdout().write_all(b"\x1b]8;;file://")?;
+    writer.stdout().write_all(canonical_path.as_bytes())?;
+    writer.stdout().write_all(b"\x1b\\")?;
+    // Only this part is visible.
+    writer.write_str(path)?;
+    writer.stdout().write_all(b"\x1b]8;;\x1b\\")?;
+    writer
+        .stdout()
+        .queue(SetForegroundColor(Color::Reset))?
+        .queue(SetAttribute(Attribute::NoUnderline))?;
+
+    Ok(())
+}
+
+pub fn write_ansi(output: &mut Vec<u8>, command: impl Command) {
+    struct FmtWriter<'a>(&'a mut Vec<u8>);
+
+    impl fmt::Write for FmtWriter<'_> {
+        fn write_str(&mut self, s: &str) -> fmt::Result {
+            self.0.extend_from_slice(s.as_bytes());
+            Ok(())
+        }
+    }
+
+    let _ = command.write_ansi(&mut FmtWriter(output));
+}

src/terminal_link.rs

@@ -1,26 +0,0 @@
-use std::{
-    fmt::{self, Display, Formatter},
-    fs,
-};
-
-pub struct TerminalFileLink<'a>(pub &'a str);
-
-impl<'a> Display for TerminalFileLink<'a> {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        let path = fs::canonicalize(self.0);
-
-        if let Some(path) = path.as_deref().ok().and_then(|path| path.to_str()) {
-            // Windows itself can't handle its verbatim paths.
-            #[cfg(windows)]
-            let path = if path.len() > 5 && &path[0..4] == r"\\?\" {
-                &path[4..]
-            } else {
-                path
-            };
-
-            write!(f, "\x1b]8;;file://{path}\x1b\\{}\x1b]8;;\x1b\\", self.0)
-        } else {
-            write!(f, "{}", self.0)
-        }
-    }
-}

src/watch.rs

@@ -72,38 +72,34 @@ pub fn watch(
 
     let mut watch_state = WatchState::new(app_state, manual_run);
 
-    watch_state.run_current_exercise()?;
+    let mut stdout = io::stdout().lock();
+    watch_state.run_current_exercise(&mut stdout)?;
 
     thread::spawn(move || terminal_event_handler(tx, manual_run));
 
     while let Ok(event) = rx.recv() {
         match event {
-            WatchEvent::Input(InputEvent::Next) => match watch_state.next_exercise()? {
+            WatchEvent::Input(InputEvent::Next) => match watch_state.next_exercise(&mut stdout)? {
                 ExercisesProgress::AllDone => break,
-                ExercisesProgress::CurrentPending => watch_state.render()?,
-                ExercisesProgress::NewPending => watch_state.run_current_exercise()?,
+                ExercisesProgress::CurrentPending => watch_state.render(&mut stdout)?,
+                ExercisesProgress::NewPending => watch_state.run_current_exercise(&mut stdout)?,
             },
-            WatchEvent::Input(InputEvent::Hint) => {
-                watch_state.show_hint()?;
-            }
+            WatchEvent::Input(InputEvent::Hint) => watch_state.show_hint(&mut stdout)?,
             WatchEvent::Input(InputEvent::List) => {
                 return Ok(WatchExit::List);
             }
             WatchEvent::Input(InputEvent::Quit) => {
-                watch_state.into_writer().write_all(QUIT_MSG)?;
+                stdout.write_all(QUIT_MSG)?;
                 break;
             }
-            WatchEvent::Input(InputEvent::Run) => watch_state.run_current_exercise()?,
-            WatchEvent::Input(InputEvent::Unrecognized) => watch_state.render()?,
+            WatchEvent::Input(InputEvent::Run) => watch_state.run_current_exercise(&mut stdout)?,
+            WatchEvent::Input(InputEvent::Unrecognized) => watch_state.render(&mut stdout)?,
             WatchEvent::FileChange { exercise_ind } => {
-                watch_state.handle_file_change(exercise_ind)?;
-            }
-            WatchEvent::TerminalResize => {
-                watch_state.render()?;
+                watch_state.handle_file_change(exercise_ind, &mut stdout)?;
             }
+            WatchEvent::TerminalResize => watch_state.render(&mut stdout)?,
             WatchEvent::NotifyErr(e) => {
-                watch_state.into_writer().write_all(NOTIFY_ERR.as_bytes())?;
-                return Err(Error::from(e));
+                return Err(Error::from(e).context(NOTIFY_ERR));
             }
             WatchEvent::TerminalEventErr(e) => {
                 return Err(Error::from(e).context("Terminal event listener failed"));

src/watch/state.rs

@@ -1,16 +1,17 @@
 use anyhow::Result;
 use crossterm::{
-    style::{style, Stylize},
-    terminal,
+    style::{
+        Attribute, Attributes, Color, ResetColor, SetAttribute, SetAttributes, SetForegroundColor,
+    },
+    terminal, QueueableCommand,
 };
 use std::io::{self, StdoutLock, Write};
 
 use crate::{
     app_state::{AppState, ExercisesProgress},
     clear_terminal,
-    exercise::{RunnableExercise, OUTPUT_CAPACITY},
-    progress_bar::progress_bar,
-    terminal_link::TerminalFileLink,
+    exercise::{solution_link_line, RunnableExercise, OUTPUT_CAPACITY},
+    term::{progress_bar, terminal_file_link},
 };
 
 #[derive(PartialEq, Eq)]
@@ -21,7 +22,6 @@ enum DoneStatus {
 }
 
 pub struct WatchState<'a> {
-    writer: StdoutLock<'a>,
     app_state: &'a mut AppState,
     output: Vec<u8>,
     show_hint: bool,
@@ -31,10 +31,7 @@ pub struct WatchState<'a> {
 
 impl<'a> WatchState<'a> {
     pub fn new(app_state: &'a mut AppState, manual_run: bool) -> Self {
-        let writer = io::stdout().lock();
-
         Self {
-            writer,
             app_state,
             output: Vec::with_capacity(OUTPUT_CAPACITY),
             show_hint: false,
@@ -43,18 +40,20 @@ impl<'a> WatchState<'a> {
         }
     }
 
-    #[inline]
-    pub fn into_writer(self) -> StdoutLock<'a> {
-        self.writer
-    }
-
-    pub fn run_current_exercise(&mut self) -> Result<()> {
+    pub fn run_current_exercise(&mut self, stdout: &mut StdoutLock) -> Result<()> {
         self.show_hint = false;
 
+        writeln!(
+            stdout,
+            "\nChecking the exercise `{}`. Please wait…",
+            self.app_state.current_exercise().name,
+        )?;
+
         let success = self
             .app_state
             .current_exercise()
-            .run_exercise(&mut self.output, self.app_state.target_dir())?;
+            .run_exercise(Some(&mut self.output), self.app_state.cmd_runner())?;
+        self.output.push(b'\n');
         if success {
             self.done_status =
                 if let Some(solution_path) = self.app_state.current_solution_path()? {
@@ -69,10 +68,15 @@ impl<'a> WatchState<'a> {
             self.done_status = DoneStatus::Pending;
         }
 
-        self.render()
+        self.render(stdout)?;
+        Ok(())
     }
 
-    pub fn handle_file_change(&mut self, exercise_ind: usize) -> Result<()> {
+    pub fn handle_file_change(
+        &mut self,
+        exercise_ind: usize,
+        stdout: &mut StdoutLock,
+    ) -> Result<()> {
         // Don't skip exercises on file changes to avoid confusion from missing exercises.
         // Skipping exercises must be explicit in the interactive list.
         // But going back to an earlier exercise on file change is fine.
@@ -81,94 +85,115 @@ impl<'a> WatchState<'a> {
         }
 
         self.app_state.set_current_exercise_ind(exercise_ind)?;
-        self.run_current_exercise()
+        self.run_current_exercise(stdout)
     }
 
     /// Move on to the next exercise if the current one is done.
-    pub fn next_exercise(&mut self) -> Result<ExercisesProgress> {
+    pub fn next_exercise(&mut self, stdout: &mut StdoutLock) -> Result<ExercisesProgress> {
         if self.done_status == DoneStatus::Pending {
             return Ok(ExercisesProgress::CurrentPending);
         }
 
-        self.app_state.done_current_exercise(&mut self.writer)
+        self.app_state.done_current_exercise(stdout)
     }
 
-    fn show_prompt(&mut self) -> io::Result<()> {
-        self.writer.write_all(b"\n")?;
-
+    fn show_prompt(&self, stdout: &mut StdoutLock) -> io::Result<()> {
         if self.manual_run {
-            write!(self.writer, "{}:run / ", 'r'.bold())?;
+            stdout.queue(SetAttribute(Attribute::Bold))?;
+            stdout.write_all(b"r")?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b":run / ")?;
         }
 
         if self.done_status != DoneStatus::Pending {
-            write!(self.writer, "{}:{} / ", 'n'.bold(), "next".underlined())?;
+            stdout.queue(SetAttribute(Attribute::Bold))?;
+            stdout.write_all(b"n")?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b":")?;
+            stdout.queue(SetAttribute(Attribute::Underlined))?;
+            stdout.write_all(b"next")?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b" / ")?;
         }
 
         if !self.show_hint {
-            write!(self.writer, "{}:hint / ", 'h'.bold())?;
+            stdout.queue(SetAttribute(Attribute::Bold))?;
+            stdout.write_all(b"h")?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b":hint / ")?;
         }
 
-        write!(self.writer, "{}:list / {}:quit ? ", 'l'.bold(), 'q'.bold())?;
+        stdout.queue(SetAttribute(Attribute::Bold))?;
+        stdout.write_all(b"l")?;
+        stdout.queue(ResetColor)?;
+        stdout.write_all(b":list / ")?;
 
-        self.writer.flush()
+        stdout.queue(SetAttribute(Attribute::Bold))?;
+        stdout.write_all(b"q")?;
+        stdout.queue(ResetColor)?;
+        stdout.write_all(b":quit ? ")?;
+
+        stdout.flush()
     }
 
-    pub fn render(&mut self) -> Result<()> {
+    pub fn render(&self, stdout: &mut StdoutLock) -> io::Result<()> {
         // Prevent having the first line shifted if clearing wasn't successful.
-        self.writer.write_all(b"\n")?;
+        stdout.write_all(b"\n")?;
+        clear_terminal(stdout)?;
 
-        clear_terminal(&mut self.writer)?;
-
-        self.writer.write_all(&self.output)?;
-        self.writer.write_all(b"\n")?;
+        stdout.write_all(&self.output)?;
 
         if self.show_hint {
-            writeln!(
-                self.writer,
-                "{}\n{}\n",
-                "Hint".bold().cyan().underlined(),
-                self.app_state.current_exercise().hint,
-            )?;
+            stdout
+                .queue(SetAttributes(
+                    Attributes::from(Attribute::Bold).with(Attribute::Underlined),
+                ))?
+                .queue(SetForegroundColor(Color::Cyan))?;
+            stdout.write_all(b"Hint")?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b"\n")?;
+
+            stdout.write_all(self.app_state.current_exercise().hint.as_bytes())?;
+            stdout.write_all(b"\n\n")?;
         }
 
         if self.done_status != DoneStatus::Pending {
-            writeln!(
-                self.writer,
-                "{}\n",
-                "Exercise done ✓
-When you are done experimenting, enter `n` to move on to the next exercise 🦀"
-                    .bold()
-                    .green(),
-            )?;
-        }
+            stdout
+                .queue(SetAttribute(Attribute::Bold))?
+                .queue(SetForegroundColor(Color::Green))?;
+            stdout.write_all("Exercise done ✓".as_bytes())?;
+            stdout.queue(ResetColor)?;
+            stdout.write_all(b"\n")?;
 
-        if let DoneStatus::DoneWithSolution(solution_path) = &self.done_status {
-            writeln!(
-                self.writer,
-                "A solution file can be found at {}\n",
-                style(TerminalFileLink(solution_path)).underlined().green(),
+            if let DoneStatus::DoneWithSolution(solution_path) = &self.done_status {
+                solution_link_line(stdout, solution_path)?;
+            }
+
+            stdout.write_all(
+                "When done experimenting, enter `n` to move on to the next exercise 🦀\n\n"
+                    .as_bytes(),
             )?;
         }
 
         let line_width = terminal::size()?.0;
-        let progress_bar = progress_bar(
+        progress_bar(
+            stdout,
             self.app_state.n_done(),
             self.app_state.exercises().len() as u16,
             line_width,
         )?;
-        writeln!(
-            self.writer,
-            "{progress_bar}Current exercise: {}",
-            self.app_state.current_exercise().terminal_link(),
-        )?;
 
-        self.show_prompt()?;
+        stdout.write_all(b"\nCurrent exercise: ")?;
+        terminal_file_link(stdout, self.app_state.current_exercise().path, Color::Blue)?;
+        stdout.write_all(b"\n\n")?;
+
+        self.show_prompt(stdout)?;
 
         Ok(())
     }
 
-    pub fn show_hint(&mut self) -> Result<()> {
+    pub fn show_hint(&mut self, stdout: &mut StdoutLock) -> io::Result<()> {
         self.show_hint = true;
-        self.render()
+        self.render(stdout)
     }
 }

src/watch/terminal_event.rs

@@ -78,7 +78,7 @@ pub fn terminal_event_handler(tx: Sender<WatchEvent>, manual_run: bool) {
                     return;
                 }
             }
-            Event::FocusGained | Event::FocusLost | Event::Mouse(_) | Event::Paste(_) => continue,
+            Event::FocusGained | Event::FocusLost | Event::Mouse(_) => continue,
         }
     };
 

tests/fixture/failure/Cargo.toml

@@ -1,20 +0,0 @@
-[package]
-name = "failure"
-edition = "2021"
-publish = false
-
-[[bin]]
-name = "compFailure"
-path = "exercises/compFailure.rs"
-
-[[bin]]
-name = "compNoExercise"
-path = "exercises/compNoExercise.rs"
-
-[[bin]]
-name = "testFailure"
-path = "exercises/testFailure.rs"
-
-[[bin]]
-name = "testNotPassed"
-path = "exercises/testNotPassed.rs"

tests/fixture/failure/exercises/testFailure.rs

@@ -1,6 +0,0 @@
-fn main() {}
-
-#[test]
-fn passing() {
-    asset!(true);
-}

tests/fixture/failure/exercises/testNotPassed.rs

@@ -1,6 +0,0 @@
-fn main() {}
-
-#[test]
-fn not_passing() {
-    assert!(false);
-}

tests/fixture/failure/info.toml

@@ -1,10 +0,0 @@
-format_version = 1
-
-[[exercises]]
-name = "compFailure"
-test = false
-hint = ""
-
-[[exercises]]
-name = "testFailure"
-hint = "Hello!"

tests/fixture/state/Cargo.toml

@@ -1,16 +0,0 @@
-[package]
-name = "state"
-edition = "2021"
-publish = false
-
-[[bin]]
-name = "pending_exercise"
-path = "exercises/pending_exercise.rs"
-
-[[bin]]
-name = "pending_test_exercise"
-path = "exercises/pending_test_exercise.rs"
-
-[[bin]]
-name = "finished_exercise"
-path = "exercises/finished_exercise.rs"

tests/fixture/state/exercises/pending_exercise.rs

@@ -1 +0,0 @@
-fn main() {}

tests/fixture/state/exercises/pending_test_exercise.rs

@@ -1,4 +0,0 @@
-fn main() {}
-
-#[test]
-fn it_works() {}

tests/fixture/state/info.toml

@@ -1,15 +0,0 @@
-format_version = 1
-
-[[exercises]]
-name = "pending_exercise"
-test = false
-hint = """"""
-
-[[exercises]]
-name = "pending_test_exercise"
-hint = """"""
-
-[[exercises]]
-name = "finished_exercise"
-test = false
-hint = """"""

tests/fixture/success/Cargo.toml

@@ -1,12 +0,0 @@
-[package]
-name = "success"
-edition = "2021"
-publish = false
-
-[[bin]]
-name = "compSuccess"
-path = "exercises/compSuccess.rs"
-
-[[bin]]
-name = "testSuccess"
-path = "exercises/testSuccess.rs"

tests/fixture/success/exercises/compSuccess.rs

@@ -1 +0,0 @@
-fn main() {}

tests/fixture/success/exercises/testSuccess.rs

@@ -1,7 +0,0 @@
-fn main() {}
-
-#[test]
-fn passing() {
-    println!("THIS TEST TOO SHALL PASS");
-    assert!(true);
-}

tests/fixture/success/info.toml

@@ -1,10 +0,0 @@
-format_version = 1
-
-[[exercises]]
-name = "compSuccess"
-test = false
-hint = """"""
-
-[[exercises]]
-name = "testSuccess"
-hint = """"""

tests/integration_tests.rs

@@ -1,134 +1,182 @@
-use assert_cmd::prelude::*;
-use std::process::Command;
+use std::{
+    env::{self, consts::EXE_SUFFIX},
+    process::{Command, Stdio},
+    str::from_utf8,
+};
 
-#[test]
-fn fails_when_in_wrong_dir() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .current_dir("tests/")
-        .assert()
-        .code(1);
+enum Output<'a> {
+    FullStdout(&'a str),
+    PartialStdout(&'a str),
+    PartialStderr(&'a str),
+}
+
+use Output::*;
+
+#[derive(Default)]
+struct Cmd<'a> {
+    current_dir: Option<&'a str>,
+    args: &'a [&'a str],
+    output: Option<Output<'a>>,
+}
+
+impl<'a> Cmd<'a> {
+    #[inline]
+    fn current_dir(&mut self, current_dir: &'a str) -> &mut Self {
+        self.current_dir = Some(current_dir);
+        self
+    }
+
+    #[inline]
+    fn args(&mut self, args: &'a [&'a str]) -> &mut Self {
+        self.args = args;
+        self
+    }
+
+    #[inline]
+    fn output(&mut self, output: Output<'a>) -> &mut Self {
+        self.output = Some(output);
+        self
+    }
+
+    fn assert(&self, success: bool) {
+        let rustlings_bin = {
+            let mut path = env::current_exe().unwrap();
+            // Pop test binary name
+            path.pop();
+            // Pop `/deps`
+            path.pop();
+
+            path.push("rustlings");
+            let mut path = path.into_os_string();
+            path.push(EXE_SUFFIX);
+            path
+        };
+
+        let mut cmd = Command::new(rustlings_bin);
+
+        if let Some(current_dir) = self.current_dir {
+            cmd.current_dir(current_dir);
+        }
+
+        cmd.args(self.args).stdin(Stdio::null());
+
+        let status = match self.output {
+            None => cmd
+                .stdout(Stdio::null())
+                .stderr(Stdio::null())
+                .status()
+                .unwrap(),
+            Some(FullStdout(stdout)) => {
+                let output = cmd.stderr(Stdio::null()).output().unwrap();
+                assert_eq!(from_utf8(&output.stdout).unwrap(), stdout);
+                output.status
+            }
+            Some(PartialStdout(stdout)) => {
+                let output = cmd.stderr(Stdio::null()).output().unwrap();
+                assert!(from_utf8(&output.stdout).unwrap().contains(stdout));
+                output.status
+            }
+            Some(PartialStderr(stderr)) => {
+                let output = cmd.stdout(Stdio::null()).output().unwrap();
+                assert!(from_utf8(&output.stderr).unwrap().contains(stderr));
+                output.status
+            }
+        };
+
+        assert_eq!(status.success(), success, "{cmd:?}");
+    }
+
+    #[inline]
+    fn success(&self) {
+        self.assert(true);
+    }
+
+    #[inline]
+    fn fail(&self) {
+        self.assert(false);
+    }
 }
 
 #[test]
-fn run_single_compile_success() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "compSuccess"])
-        .current_dir("tests/fixture/success/")
-        .assert()
+fn run_compilation_success() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["run", "compilation_success"])
         .success();
 }
 
 #[test]
-fn run_single_compile_failure() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "compFailure"])
-        .current_dir("tests/fixture/failure/")
-        .assert()
-        .code(1);
+fn run_compilation_failure() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["run", "compilation_failure"])
+        .fail();
 }
 
 #[test]
-fn run_single_test_success() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "testSuccess"])
-        .current_dir("tests/fixture/success/")
-        .assert()
+fn run_test_success() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["run", "test_success"])
+        .output(PartialStdout("\nOutput from `main` function\n"))
         .success();
 }
 
 #[test]
-fn run_single_test_failure() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "testFailure"])
-        .current_dir("tests/fixture/failure/")
-        .assert()
-        .code(1);
+fn run_test_failure() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["run", "test_failure"])
+        .fail();
 }
 
 #[test]
-fn run_single_test_not_passed() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "testNotPassed.rs"])
-        .current_dir("tests/fixture/failure/")
-        .assert()
-        .code(1);
+fn run_exercise_not_in_info() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["run", "not_in_info"])
+        .fail();
 }
 
 #[test]
-fn run_single_test_no_exercise() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "compNoExercise.rs"])
-        .current_dir("tests/fixture/failure")
-        .assert()
-        .code(1);
+fn reset_without_exercise_name() {
+    Cmd::default().args(&["reset"]).fail();
 }
 
 #[test]
-fn reset_single_exercise() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["reset", "intro1"])
-        .assert()
-        .code(0);
+fn hint() {
+    Cmd::default()
+        .current_dir("tests/test_exercises")
+        .args(&["hint", "test_failure"])
+        .output(FullStdout("The answer to everything: 42\n"))
+        .success();
 }
 
 #[test]
-fn reset_no_exercise() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .arg("reset")
-        .assert()
-        .code(2)
-        .stderr(predicates::str::contains(
-            "required arguments were not provided",
-        ));
-}
+fn init() {
+    let test_dir = tempfile::TempDir::new().unwrap();
+    let test_dir = test_dir.path().to_str().unwrap();
 
-#[test]
-fn get_hint_for_single_test() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["hint", "testFailure"])
-        .current_dir("tests/fixture/failure")
-        .assert()
-        .code(0)
-        .stdout("Hello!\n");
-}
+    Cmd::default().current_dir(test_dir).fail();
 
-#[test]
-fn run_compile_exercise_does_not_prompt() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "pending_exercise"])
-        .current_dir("tests/fixture/state")
-        .assert()
-        .code(0);
-}
+    Cmd::default()
+        .current_dir(test_dir)
+        .args(&["init"])
+        .success();
 
-#[test]
-fn run_test_exercise_does_not_prompt() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "pending_test_exercise"])
-        .current_dir("tests/fixture/state")
-        .assert()
-        .code(0);
-}
+    // Running `init` after a successful initialization.
+    Cmd::default()
+        .current_dir(test_dir)
+        .args(&["init"])
+        .output(PartialStderr("`cd rustlings`"))
+        .fail();
 
-#[test]
-fn run_single_test_success_with_output() {
-    Command::cargo_bin("rustlings")
-        .unwrap()
-        .args(["run", "testSuccess"])
-        .current_dir("tests/fixture/success/")
-        .assert()
-        .code(0)
-        .stdout(predicates::str::contains("THIS TEST TOO SHALL PASS"));
+    let initialized_dir = format!("{test_dir}/rustlings");
+
+    // Running `init` in the initialized directory.
+    Cmd::default()
+        .current_dir(&initialized_dir)
+        .args(&["init"])
+        .output(PartialStderr("already initialized"))
+        .fail();
 }

tests/test_exercises/dev/Cargo.toml

@@ -0,0 +1,11 @@
+bin = [
+  { name = "compilation_success", path = "../exercises/compilation_success.rs" },
+  { name = "compilation_failure", path = "../exercises/compilation_failure.rs" },
+  { name = "test_success", path = "../exercises/test_success.rs" },
+  { name = "test_failure", path = "../exercises/test_failure.rs" },
+]
+
+[package]
+name = "test_exercises"
+edition = "2021"
+publish = false

tests/test_exercises/exercises/test_failure.rs

@@ -0,0 +1,9 @@
+fn main() {}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn fails() {
+        assert!(false);
+    }
+}

tests/test_exercises/exercises/test_success.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("Output from `main` function");
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn passes() {}
+}

tests/test_exercises/info.toml

@@ -0,0 +1,19 @@
+format_version = 1
+
+[[exercises]]
+name = "compilation_success"
+test = false
+hint = ""
+
+[[exercises]]
+name = "compilation_failure"
+test = false
+hint = ""
+
+[[exercises]]
+name = "test_success"
+hint = ""
+
+[[exercises]]
+name = "test_failure"
+hint = "The answer to everything: 42"