release: 4.2.0

feat(try_from_into): Add tests (#571 )
Co-authored-by: Volodymyr Patuta <6977238-fiplox@users.noreply.gitlab.com>
2025-12-26 00:11:49 +02:00 · 2020-11-07 14:21:10 +01:00 · 2020-11-07 14:01:39 +01:00 · 2020-11-07 13:54:14 +01:00 · 2020-11-07 13:53:35 +01:00 · 2020-11-05 19:30:50 -05:00
78 changed files with 3142 additions and 421 deletions
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
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--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,8 @@
 target/
 **/*.rs.bk
 .DS_Store
+*.pdb
+exercises/clippy/Cargo.toml
+exercises/clippy/Cargo.lock
+.idea
+.vscode
--- a/.gitpod.yml
+++ b/.gitpod.yml
@@ -0,0 +1,7 @@
+tasks:
+  - init: /workspace/rustlings/install.sh
+    command: /workspace/.cargo/bin/rustlings watch
+
+vscode:
+  extensions:
+    - rust-lang.rust@0.7.8:CvNqMTgDdt3UXt+6BCDTVg==
--- a/.replit
+++ b/.replit
@@ -0,0 +1,2 @@
+language = "rust"
+run = "[ -x ~/.cargo/bin/rustlings ] && ~/.cargo/bin/rustlings watch || ./install.sh"
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,11 +0,0 @@
-language: rust
-rust:
-  - stable
-  - beta
-  - nightly
-script: cargo test --verbose
-matrix:
-  allow_failures:
-    - rust: nightly
-  fast_finish: true
-cache: cargo
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,171 @@
+<a name="4.2.0"></a>
+## 4.2.0 (2020-11-07)
+
+#### Features
+
+*   Add HashMap exercises ([633c00cf](https://github.com/rust-lang/rustlings/commit/633c00cf8071e1e82959a3010452a32f34f29fc9))
+*   Add Vec exercises ([0c12fa31](https://github.com/rust-lang/rustlings/commit/0c12fa31c57c03c6287458a0a8aca7afd057baf6))
+* **primitive_types6:**  Add a test (#548) ([2b1fb2b7](https://github.com/rust-lang/rustlings/commit/2b1fb2b739bf9ad8d6b7b12af25fee173011bfc4))
+* **try_from_into:**  Add tests (#571) ([95ccd926](https://github.com/rust-lang/rustlings/commit/95ccd92616ae79ba287cce221101e0bbe4f68cdc))
+
+#### Bug Fixes
+
+*   log error output when inotify limit is exceeded ([d61b4e5a](https://github.com/rust-lang/rustlings/commit/d61b4e5a13b44d72d004082f523fa1b6b24c1aca))
+*   more unique temp_file ([5643ef05](https://github.com/rust-lang/rustlings/commit/5643ef05bc81e4a840e9456f4406a769abbe1392))
+* **installation:**  Update the MinRustVersion ([21bfb2d4](https://github.com/rust-lang/rustlings/commit/21bfb2d4777429c87d8d3b5fbf0ce66006dcd034))
+* **iterators2:**  Update description (#578) ([197d3a3d](https://github.com/rust-lang/rustlings/commit/197d3a3d8961b2465579218a6749b2b2cefa8ddd))
+* **primitive_types6:**
+  *  remove 'unused doc comment' warning ([472d8592](https://github.com/rust-lang/rustlings/commit/472d8592d65c8275332a20dfc269e7ac0d41bc88))
+  *  missing comma in test ([4fb230da](https://github.com/rust-lang/rustlings/commit/4fb230daf1251444fcf29e085cee222a91f8a37e))
+* **quiz3:**  Second test is for odd numbers, not even. (#553) ([18e0bfef](https://github.com/rust-lang/rustlings/commit/18e0bfef1de53071e353ba1ec5837002ff7290e6))
+
+<a name="4.1.0"></a>
+## 4.1.0 (2020-10-05)
+
+#### Bug Fixes
+
+*   Update rustlings version in Cargo.lock ([1cc40bc9](https://github.com/rust-lang/rustlings/commit/1cc40bc9ce95c23d56f6d91fa1c4deb646231fef))
+* **arc1:**  index mod should equal thread count ([b4062ef6](https://github.com/rust-lang/rustlings/commit/b4062ef6993e80dac107c4093ea85166ad3ee0fa))
+* **enums3:**  Update Message::ChangeColor to take a tuple. (#457) ([4b6540c7](https://github.com/rust-lang/rustlings/commit/4b6540c71adabad647de8a09e57295e7c7c7d794))
+* **exercises:**  adding question mark to quiz2 ([101072ab](https://github.com/rust-lang/rustlings/commit/101072ab9f8c80b40b8b88cb06cbe38aca2481c5))
+* **generics3:**  clarify grade change ([47f7672c](https://github.com/rust-lang/rustlings/commit/47f7672c0307732056e7426e81d351f0dd7e22e5))
+* **structs3:**  Small adjustment of variable name ([114b54cb](https://github.com/rust-lang/rustlings/commit/114b54cbdb977234b39e5f180d937c14c78bb8b2))
+* **using_as:**  Add test so that proper type is returned. (#512) ([3286c5ec](https://github.com/rust-lang/rustlings/commit/3286c5ec19ea5fb7ded81d047da5f8594108a490))
+
+#### Features
+
+*   Added iterators1.rs exercise ([9642f5a3](https://github.com/rust-lang/rustlings/commit/9642f5a3f686270a4f8f6ba969919ddbbc4f7fdd))
+*   Add ability to run rustlings on repl.it (#471) ([8f7b5bd0](https://github.com/rust-lang/rustlings/commit/8f7b5bd00eb83542b959830ef55192d2d76db90a))
+*   Add gitpod support (#473) ([4821a8be](https://github.com/rust-lang/rustlings/commit/4821a8be94af4f669042a06ab917934cfacd032f))
+*   Remind the user of the hint option (#425) ([816b1f5e](https://github.com/rust-lang/rustlings/commit/816b1f5e85d6cc6e72673813a85d0ada2a8f84af))
+*   Remind the user of the hint option (#425) ([9f61db5d](https://github.com/rust-lang/rustlings/commit/9f61db5dbe38538cf06571fcdd5f806e7901e83a))
+* **cli:**  Added 'cls' command to 'watch' mode (#474) ([4f2468e1](https://github.com/rust-lang/rustlings/commit/4f2468e14f574a93a2e9b688367b5752ed96ae7b))
+* **try_from_into:**  Add insufficient length test (#469) ([523d18b8](https://github.com/rust-lang/rustlings/commit/523d18b873a319f7c09262f44bd40e2fab1830e5))
+
+<a name="4.0.0"></a>
+## 4.0.0 (2020-07-08)
+
+#### Breaking Changes
+
+*   Add a --nocapture option to display test harnesses' outputs ([8ad5f9bf](https://github.com/rust-lang/rustlings/commit/8ad5f9bf531a4848b1104b7b389a20171624c82f))
+*   Rename test to quiz, fixes #244 ([010a0456](https://github.com/rust-lang/rustlings/commit/010a04569282149cea7f7a76fc4d7f4c9f0f08dd))
+
+#### Features
+
+*   Add traits README ([173bb141](https://github.com/rust-lang/rustlings/commit/173bb14140c5530cbdb59e53ace3991a99d804af))
+*   Add box1.rs exercise ([7479a473](https://github.com/rust-lang/rustlings/commit/7479a4737bdcac347322ad0883ca528c8675e720))
+*   Rewrite try_from_into (#393) ([763aa6e3](https://github.com/rust-lang/rustlings/commit/763aa6e378a586caae2d8d63755a85eeba227933))
+*   Add if2 exercise ([1da84b5f](https://github.com/rust-lang/rustlings/commit/1da84b5f7c489f65bd683c244f13c7d1ee812df0))
+*   Added exercise structs3.rs ([b66e2e09](https://github.com/rust-lang/rustlings/commit/b66e2e09622243e086a0f1258dd27e1a2d61c891))
+*   Add exercise variables6 covering const (#352) ([5999acd2](https://github.com/rust-lang/rustlings/commit/5999acd24a4f203292be36e0fd18d385887ec481))
+
+#### Bug Fixes
+
+*   Change then to than ([ddd98ad7](https://github.com/rust-lang/rustlings/commit/ddd98ad75d3668fbb10eff74374148aa5ed2344d))
+*   rename quiz1 to tests1 in info (#420) ([0dd1c6ca](https://github.com/rust-lang/rustlings/commit/0dd1c6ca6b389789e0972aa955fe17aa15c95f29))
+*   fix quiz naming inconsistency (#421) ([5563adbb](https://github.com/rust-lang/rustlings/commit/5563adbb890587fc48fbbc9c4028642687f1e85b))
+*   confine the user further in variable exercises ([06ef4cc6](https://github.com/rust-lang/rustlings/commit/06ef4cc654e75d22a526812919ee49b8956280bf))
+*   update iterator and macro text for typos and clarity ([95900828](https://github.com/rust-lang/rustlings/commit/959008284834bece0196a01e17ac69a7e3590116))
+*   update generics2       closes #362 ([964c974a](https://github.com/rust-lang/rustlings/commit/964c974a0274199d755073b917c2bc5da0c9b4f1))
+*   confusing comment in conversions/try_from_into.rs ([c9e4f2cf](https://github.com/rust-lang/rustlings/commit/c9e4f2cfb4c48d0b7451263cfb43b9426438122d))
+* **arc1:**  Passively introduce attributes (#429) ([113cdae2](https://github.com/rust-lang/rustlings/commit/113cdae2d4e4c55905e8056ad326ede7fd7de356))
+* **box1:**  fix comment typo (#426) ([bb2ca251](https://github.com/rust-lang/rustlings/commit/bb2ca251106b27a7272d9a30872904dd1376654c))
+* **errorsn:**  Try harder to confine the user. (#388) ([2b20c8a0](https://github.com/rust-lang/rustlings/commit/2b20c8a0f5774d07c58d110d75879f33fc6273b5))
+* **from_into.rs:**  typo ([a901499e](https://github.com/rust-lang/rustlings/commit/a901499ededd3ce1995164700514fe4e9a0373ea))
+* **generics2:**  Guide students to the answer (#430) ([e6bd8021](https://github.com/rust-lang/rustlings/commit/e6bd8021d9a7dd06feebc30c9d5f953901d7b419))
+* **installation:**
+  *  Provide a backup git reference when tag can't be curl ([9e4fb100](https://github.com/rust-lang/rustlings/commit/9e4fb1009f1c9e3433915c03e22c2af422e5c5fe))
+  *  Check if python is available while checking for git,rustc and cargo ([9cfb617d](https://github.com/rust-lang/rustlings/commit/9cfb617d5b0451b4b51644a1298965390cda9884))
+* **option1:**
+  *  Don't add only zeros to the numbers array ([cce6a442](https://github.com/rust-lang/rustlings/commit/cce6a4427718724a9096800754cd3abeca6a1580))
+  *  Add cast to usize, as it is confusing in the context of an exercise about Option ([f6cffc7e](https://github.com/rust-lang/rustlings/commit/f6cffc7e487b42f15a6f958e49704c93a8d4465b))
+* **option2:**  Add TODO to comments (#400) ([10967bce](https://github.com/rust-lang/rustlings/commit/10967bce57682812dc0891a9f9757da1a9d87404))
+* **options1:**  Add hint about Array Initialization (#389) ([9f75554f](https://github.com/rust-lang/rustlings/commit/9f75554f2a30295996f03f0160b98c0458305502))
+* **test2:**  name of type String and &str (#394) ([d6c0a688](https://github.com/rust-lang/rustlings/commit/d6c0a688e6a96f93ad60d540d4b326f342fc0d45))
+* **variables6:**  minor typo (#419) ([524e17df](https://github.com/rust-lang/rustlings/commit/524e17df10db95f7b90a0f75cc8997182a8a4094))
+
+<a name="3.0.0"></a>
+## 3.0.0 (2020-04-11)
+
+#### Breaking Changes
+
+* make "compile" exercises print output (#278) ([3b6d5c](https://github.com/fmoko/rustlings/commit/3b6d5c3aaa27a242a832799eb66e96897d26fde3))
+
+#### Bug Fixes
+
+* **primitive_types:** revert primitive_types4 (#296) ([b3a3351e](https://github.com/rust-lang/rustlings/commit/b3a3351e8e6a0bdee07077d7b0382953821649ae))
+* **run:**  compile clippy exercise files (#295) ([3ab084a4](https://github.com/rust-lang/rustlings/commit/3ab084a421c0f140ae83bf1fc3f47b39342e7373))
+* **conversions:**
+  * add additional test to meet exercise rules (#284) ([bc22ec3](https://github.com/fmoko/rustlings/commit/bc22ec382f843347333ef1301fc1bad773657f38))
+  * remove duplicate not done comment (#292) ([dab90f](https://github.com/fmoko/rustlings/commit/dab90f7b91a6000fe874e3d664f244048e5fa342))
+* don't hardcode documentation version for traits (#288) ([30e6af](https://github.com/fmoko/rustlings/commit/30e6af60690c326fb5d3a9b7335f35c69c09137d))
+
+#### Features
+
+*   add Option2 exercise (#290) ([86b5c08b](https://github.com/rust-lang/rustlings/commit/86b5c08b9bea1576127a7c5f599f5752072c087d))
+*   add excercise for option (#282) ([135e5d47](https://github.com/rust-lang/rustlings/commit/135e5d47a7c395aece6f6022117fb20c82f2d3d4))
+*   add new exercises for generics (#280) ([76be5e4e](https://github.com/rust-lang/rustlings/commit/76be5e4e991160f5fd9093f03ee2ba260e8f7229))
+* **ci:**  add buildkite config ([b049fa2c](https://github.com/rust-lang/rustlings/commit/b049fa2c84dba0f0c8906ac44e28fd45fba51a71))
+
+<a name="2.2.1"></a>
+### 2.2.1 (2020-02-27)
+
+#### Bug Fixes
+
+*   Re-add cloning the repo to install scripts ([3d9b03c5](https://github.com/rust-lang/rustlings/commit/3d9b03c52b8dc51b140757f6fd25ad87b5782ef5))
+
+#### Features
+
+*   Add clippy lints (#269) ([1e2fd9c9](https://github.com/rust-lang/rustlings/commit/1e2fd9c92f8cd6e389525ca1a999fca4c90b5921))
+
+<a name="2.2.0"></a>
+## 2.2.0 (2020-02-25)
+
+
+#### Bug Fixes
+
+*   Update deps to version compatable with aarch64-pc-windows (#263) ([19a93428](https://github.com/rust-lang/rustlings/commit/19a93428b3c73d994292671f829bdc8e5b7b3401))
+* **docs:**
+  * Added a necessary step to Windows installation process (#242) ([3906efcd](https://github.com/rust-lang/rustlings/commit/3906efcd52a004047b460ed548037093de3f523f))
+  * Fixed mangled sentence from book; edited for clarity (#266) ([ade52ff](https://github.com/rust-lang/rustlings/commit/ade52ffb739987287ddd5705944c8777705faed9))
+  * Updated iterators readme to account for iterators4 exercise (#273) ([bec8e3a](https://github.com/rust-lang/rustlings/commit/bec8e3a644cbd88db1c73ea5f1d8a364f4a34016))
+* **installation:**  make fatal errors more obvious (#272) ([17d0951e](https://github.com/rust-lang/rustlings/commit/17d0951e66fda8e11b204d5c4c41a0d5e22e78f7))
+* **iterators2:**
+  *  Remove reference to missing iterators2.rs (#245) ([419f7797](https://github.com/rust-lang/rustlings/commit/419f7797f294e4ce6a2b883199731b5bde77d262))
+* **as_ref_mut:** Enable a test and improve per clippy's suggestion (#256) ([dfdf809](https://github.com/rust-lang/rustlings/commit/dfdf8093ebbd4145864995627b812780de52f902))
+* **tests1:**
+  * Change test command ([fe10e06c](https://github.com/rust-lang/rustlings/commit/fe10e06c3733ddb4a21e90d09bf79bfe618e97ce)
+  * Correct test command in tests1.rs comment (#263) ([39fa7ae](https://github.com/rust-lang/rustlings/commit/39fa7ae8b70ad468da49b06f11b2383135a63bcf))
+
+#### Features
+
+*   Add variables5.rs exercise (#264) ([0c73609e](https://github.com/rust-lang/rustlings/commit/0c73609e6f2311295e95d6f96f8c747cfc4cba03))
+*   Show a completion message when watching (#253) ([d25ee55a](https://github.com/rust-lang/rustlings/commit/d25ee55a3205882d35782e370af855051b39c58c))
+*   Add type conversion and parsing exercises (#249) ([0c85dc11](https://github.com/rust-lang/rustlings/commit/0c85dc1193978b5165491b99cc4922caf8d14a65))
+*   Created consistent money unit (#258) ([fd57f8f](https://github.com/rust-lang/rustlings/commit/fd57f8f2c1da2af8ddbebbccec214e6f40f4dbab))
+*   Enable test for exercise test4 (#276) ([8b971ff](https://github.com/rust-lang/rustlings/commit/8b971ffab6079a706ac925f5917f987932b55c07))
+*   Added traits exercises (#274 but specifically #216, which originally added
+    this :heart:) ([b559cdd](https://github.com/rust-lang/rustlings/commit/b559cdd73f32c0d0cfc1feda39f82b3e3583df17))
+
+
+<a name="2.1.0"></a>
+## 2.1.0 (2019-11-27)
+
+#### Bug Fixes
+
+* add line numbers in several exercises and hints ([b565c4d3](https://github.com/rust-lang/rustlings/commit/b565c4d3e74e8e110bef201a082fa1302722a7c3))
+* **arc1:**  Fix some words in the comment ([c42c3b21](https://github.com/rust-lang/rustlings/commit/c42c3b2101df9164c8cd7bb344def921e5ba3e61))
+* **enums:**  Add link to chapter on pattern syntax (#242) ([615ce327](https://github.com/rust-lang/rustlings/commit/615ce3279800c56d89f19d218ccb7ef576624feb))
+* **primitive_types4:**
+  *  update outdated hint ([4c5189df](https://github.com/rust-lang/rustlings/commit/4c5189df2bdd9a231f6b2611919ba5aa14da0d3f))
+  *  update outdated comment ([ded2c034](https://github.com/rust-lang/rustlings/commit/ded2c034ba93fa1e3c2c2ea16b83abc1a57265e8))
+* **strings2:**  update line number in hint ([a09f684f](https://github.com/rust-lang/rustlings/commit/a09f684f05c58d239a6fc59ec5f81c2533e8b820))
+* **variables1:**  Correct wrong word in comment ([fda5a470](https://github.com/rust-lang/rustlings/commit/fda5a47069e0954f16a04e8e50945e03becb71a5))
+
+#### Features
+
+* **watch:**  show hint while watching ([8143d57b](https://github.com/rust-lang/rustlings/commit/8143d57b4e88c51341dd4a18a14c536042cc009c))
+
 <a name="2.0.0"></a>
 ## 2.0.0 (2019-11-12)

--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,13 +1,5 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-[[package]]
-name = "aho-corasick"
-version = "0.6.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "aho-corasick"
 version = "0.7.3"
@@ -21,7 +13,7 @@ name = "ansi_term"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -42,7 +34,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
 "termion 1.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -74,17 +66,6 @@ dependencies = [
 "vec_map 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

-[[package]]
-name = "clicolors-control"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "clicolors-control"
 version = "1.0.0"
@@ -93,7 +74,7 @@ dependencies = [
 "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -106,23 +87,7 @@ dependencies = [

 [[package]]
 name = "console"
-version = "0.6.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "clicolors-control 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "console"
-version = "0.7.5"
+version = "0.7.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -134,7 +99,22 @@ dependencies = [
 "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "console"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "clicolors-control 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "encode_unicode 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -219,18 +199,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
 name = "indicatif"
-version = "0.9.0"
+version = "0.10.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "console 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "console 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "number_prefix 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
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-version = "0.6.1"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
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@@ -269,11 +250,6 @@ dependencies = [
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-[[package]]
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-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
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@@ -356,7 +332,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
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 "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
@@ -366,20 +342,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
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-version = "4.0.12"
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- "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
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- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
@@ -390,6 +365,14 @@ dependencies = [
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+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
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@@ -417,7 +400,7 @@ dependencies = [
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- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
@@ -477,7 +460,7 @@ dependencies = [
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- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
@@ -525,7 +508,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
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 "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
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- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
@@ -579,18 +562,6 @@ dependencies = [
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-[[package]]
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-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
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 [[package]]
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@@ -603,14 +574,6 @@ dependencies = [
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-[[package]]
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 [[package]]
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@@ -629,14 +592,14 @@ dependencies = [

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- "console 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
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- "notify 4.0.12 (registry+https://github.com/rust-lang/crates.io-index)",
+ "indicatif 0.10.3 (registry+https://github.com/rust-lang/crates.io-index)",
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- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -817,7 +780,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
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 dependencies = [
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@@ -839,7 +802,7 @@ name = "winapi-util"
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 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -857,7 +820,6 @@ dependencies = [
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@@ -882,13 +843,12 @@ dependencies = [
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@@ -900,8 +860,9 @@ dependencies = [
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@@ -923,9 +884,7 @@ dependencies = [
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-"checksum regex-syntax 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)" = "7d707a4fa2637f2dca2ef9fd02225ec7661fe01a53623c1e6515b6916511f7a7"
 "checksum regex-syntax 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)" = "dcfd8681eebe297b81d98498869d4aae052137651ad7b96822f09ceb690d0a96"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
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@@ -953,7 +912,7 @@ dependencies = [
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--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,14 +1,14 @@
 [package]
 name = "rustlings"
-version = "2.0.0"
-authors = ["Marisa <mokou@posteo.de>", "Carol (Nichols || Goulding) <carol.nichols@gmail.com"]
+version = "4.2.0"
+authors = ["Marisa <mokou@posteo.de>", "Carol (Nichols || Goulding) <carol.nichols@gmail.com>"]
 edition = "2018"

 [dependencies]
 clap = "2.32.0"
-indicatif = "0.9.0"
-console = "0.6.2"
-notify = "4.0.0"
+indicatif = "0.10.3"
+console = "0.7.7"
+notify = "4.0.15"
 toml = "0.4.10"
 regex = "1.1.6"
 serde = {version = "1.0.10", features = ["derive"]}
--- a/README.md
+++ b/README.md
@@ -1,12 +1,15 @@
 ![crab pet](https://i.imgur.com/LbZJgmm.gif)
+<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
+[![All Contributors](https://img.shields.io/badge/all_contributors-68-orange.svg?style=flat-square)](#contributors-)
+<!-- ALL-CONTRIBUTORS-BADGE:END -->

-# rustlings 🦀❤️
+# rustlings 🦀❤️ [![Build status](https://badge.buildkite.com/7af93d81dc522c67a1ec8e33ff5705861b1cb36360b774807f.svg)](https://buildkite.com/mokou/rustlings)

 Greetings and welcome to `rustlings`. This project contains small exercises to get you used to reading and writing Rust code. This includes reading and responding to compiler messages!

 _...looking for the old, web-based version of Rustlings? Try [here](https://github.com/rust-lang/rustlings/tree/rustlings-1)_

-Alternatively, for a first-time Rust learner, there's several other resources:
+Alternatively, for a first-time Rust learner, there are several other resources:

 - [The Book](https://doc.rust-lang.org/book/index.html) - The most comprehensive resource for learning Rust, but a bit theoretical sometimes. You will be using this along with Rustlings!
 - [Rust By Example](https://doc.rust-lang.org/rust-by-example/index.html) - Learn Rust by solving little exercises! It's almost like `rustlings`, but online
@@ -15,8 +18,6 @@ Alternatively, for a first-time Rust learner, there's several other resources:

 _Note: If you're on MacOS, make sure you've installed Xcode and its developer tools by typing `xcode-select --install`._

-_Note: If you have Xcode 10+ installed, you also need to install the package file found at `/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg`._
-
 You will need to have Rust installed. You can get it by visiting https://rustup.rs. This'll also install Cargo, Rust's package/project manager.

 ## MacOS/Linux
@@ -33,14 +34,26 @@ This will install Rustlings and give you access to the `rustlings` command. Run

 ## Windows

-You can run:
+In PowerShell, set `ExecutionPolicy` to `RemoteSigned`:

 ```ps
-Invoke-WebRequest https://git.io/rustlings-win | Select-Object -ExpandProperty Content | Out-File $env:TMP/install_rustlings.ps1; Unblock-File $env:TMP/install_rustlings.ps1; Invoke-Expression $env:TMP/install_rustlings.ps1
+Set-ExecutionPolicy RemoteSigned
+```
+
+Then, you can run:
+
+```ps
+Start-BitsTransfer -Source https://git.io/rustlings-win -Destination $env:TMP/install_rustlings.ps1; Unblock-File $env:TMP/install_rustlings.ps1; Invoke-Expression $env:TMP/install_rustlings.ps1
 ```

 To install Rustlings. Same as on MacOS/Linux, you will have access to the `rustlings` command after it.

+## Browser:
+
+[Run on Repl.it](https://repl.it/github/rust-lang/rustlings)
+
+[Open in Gitpod](https://gitpod.io/#https://github.com/rust-lang/rustlings)
+
 ## Manually

 Basically: Clone the repository, checkout to the latest tag, run `cargo install`.
@@ -48,7 +61,7 @@ Basically: Clone the repository, checkout to the latest tag, run `cargo install`
 ```bash
 git clone https://github.com/rust-lang/rustlings
 cd rustlings
-git checkout tags/2.0.0 # or whatever the latest version is (find out at https://github.com/rust-lang/rustlings/releases/latest)
+git checkout tags/4.2.0 # or whatever the latest version is (find out at https://github.com/rust-lang/rustlings/releases/latest)
 cargo install --force --path .
 ```

@@ -63,7 +76,7 @@ Then, same as above, run `rustlings` to get started.

 The exercises are sorted by topic and can be found in the subdirectory `rustlings/exercises/<topic>`. For every topic there is an additional README file with some resources to get you started on the topic. We really recommend that you have a look at them before you start.

-The task is simple. Most exercises contain an error that keep it from compiling, and it's up to you to fix it! Some exercises are also run as tests, but rustlings handles them all the same. To run the exercises in the recommended order, execute:
+The task is simple. Most exercises contain an error that keeps them from compiling, and it's up to you to fix it! Some exercises are also run as tests, but rustlings handles them all the same. To run the exercises in the recommended order, execute:

 ```bash
 rustlings watch
@@ -92,7 +105,18 @@ rustlings hint myExercise1

 ## Testing yourself

-After every couple of sections, there will be a test that'll test your knowledge on a bunch of sections at once. These tests are found in `exercises/testN.rs`.
+After every couple of sections, there will be a quiz that'll test your knowledge on a bunch of sections at once. These quizzes are found in `exercises/quizN.rs`.
+
+## Continuing On
+
+Once you've completed Rustlings, put your new knowledge to good use! Continue practicing your Rust skills by building your own projects, contributing to Rustlings, or finding other open-source projects to contribute to.
+
+If you'd like to uninstall Rustlings, you can do so by invoking cargo and removing the rustlings directory:
+
+```bash
+cargo uninstall rustlings
+rm -r rustlings/ # or on Windows: rmdir /s rustlings
+```

 ## Completion

@@ -116,7 +140,104 @@ If you are interested in improving or adding new ones, please feel free to contr

 See [CONTRIBUTING.md](./CONTRIBUTING.md).

-## Credits
+## Contributors ✨

-`rustlings` was originally written by [Carol](https://github.com/carols10cents)!
+Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):

+<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<table>
+  <tr>
+    <td align="center"><a href="http://carol-nichols.com"><img src="https://avatars2.githubusercontent.com/u/193874?v=4" width="100px;" alt=""/><br /><sub><b>Carol (Nichols &#124;&#124; Goulding)</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=carols10cents" title="Code">💻</a> <a href="#content-carols10cents" title="Content">🖋</a></td>
+    <td align="center"><a href="https://twitter.com/QuietMisdreavus"><img src="https://avatars2.githubusercontent.com/u/5217170?v=4" width="100px;" alt=""/><br /><sub><b>QuietMisdreavus</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=QuietMisdreavus" title="Code">💻</a> <a href="#content-QuietMisdreavus" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/robertlugg"><img src="https://avatars0.githubusercontent.com/u/6054540?v=4" width="100px;" alt=""/><br /><sub><b>Robert M Lugg</b></sub></a><br /><a href="#content-robertlugg" title="Content">🖋</a></td>
+    <td align="center"><a href="https://hynek.me/about/"><img src="https://avatars3.githubusercontent.com/u/41240?v=4" width="100px;" alt=""/><br /><sub><b>Hynek Schlawack</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=hynek" title="Code">💻</a></td>
+    <td align="center"><a href="https://spacekookie.de"><img src="https://avatars0.githubusercontent.com/u/7669898?v=4" width="100px;" alt=""/><br /><sub><b>Katharina Fey</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=spacekookie" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/lukabavdaz"><img src="https://avatars0.githubusercontent.com/u/9624558?v=4" width="100px;" alt=""/><br /><sub><b>lukabavdaz</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=lukabavdaz" title="Code">💻</a> <a href="#content-lukabavdaz" title="Content">🖋</a></td>
+    <td align="center"><a href="http://vestera.as"><img src="https://avatars2.githubusercontent.com/u/4187449?v=4" width="100px;" alt=""/><br /><sub><b>Erik Vesteraas</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=evestera" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/Delet0r"><img src="https://avatars1.githubusercontent.com/u/23195618?v=4" width="100px;" alt=""/><br /><sub><b>delet0r</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Delet0r" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="http://phinary.ca"><img src="https://avatars1.githubusercontent.com/u/10522375?v=4" width="100px;" alt=""/><br /><sub><b>Shaun Bennett</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=shaunbennett" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/abagshaw"><img src="https://avatars2.githubusercontent.com/u/8594541?v=4" width="100px;" alt=""/><br /><sub><b>Andrew Bagshaw</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=abagshaw" title="Code">💻</a></td>
+    <td align="center"><a href="https://ai6ua.net/"><img src="https://avatars2.githubusercontent.com/u/175578?v=4" width="100px;" alt=""/><br /><sub><b>Kyle Isom</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=kisom" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/ColinPitrat"><img src="https://avatars3.githubusercontent.com/u/1541863?v=4" width="100px;" alt=""/><br /><sub><b>Colin Pitrat</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ColinPitrat" title="Code">💻</a></td>
+    <td align="center"><a href="https://zacanger.com"><img src="https://avatars3.githubusercontent.com/u/12520493?v=4" width="100px;" alt=""/><br /><sub><b>Zac Anger</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=zacanger" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/mgeier"><img src="https://avatars1.githubusercontent.com/u/705404?v=4" width="100px;" alt=""/><br /><sub><b>Matthias Geier</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=mgeier" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/cjpearce"><img src="https://avatars1.githubusercontent.com/u/3453268?v=4" width="100px;" alt=""/><br /><sub><b>Chris Pearce</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=cjpearce" title="Code">💻</a></td>
+    <td align="center"><a href="https://yvan-sraka.github.io"><img src="https://avatars2.githubusercontent.com/u/705213?v=4" width="100px;" alt=""/><br /><sub><b>Yvan Sraka</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=yvan-sraka" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/dendi239"><img src="https://avatars3.githubusercontent.com/u/16478650?v=4" width="100px;" alt=""/><br /><sub><b>Denys Smirnov</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=dendi239" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/eddyp"><img src="https://avatars2.githubusercontent.com/u/123772?v=4" width="100px;" alt=""/><br /><sub><b>eddyp</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=eddyp" title="Code">💻</a></td>
+    <td align="center"><a href="http://about.me/BrianKung"><img src="https://avatars1.githubusercontent.com/u/2836167?v=4" width="100px;" alt=""/><br /><sub><b>Brian Kung</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=briankung" title="Code">💻</a> <a href="#content-briankung" title="Content">🖋</a></td>
+    <td align="center"><a href="https://rcousineau.gitlab.io"><img src="https://avatars3.githubusercontent.com/u/281039?v=4" width="100px;" alt=""/><br /><sub><b>Russell</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=miller-time" title="Code">💻</a></td>
+    <td align="center"><a href="http://danwilhelm.com"><img src="https://avatars3.githubusercontent.com/u/6137185?v=4" width="100px;" alt=""/><br /><sub><b>Dan Wilhelm</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=danwilhelm" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/Jesse-Cameron"><img src="https://avatars3.githubusercontent.com/u/3723654?v=4" width="100px;" alt=""/><br /><sub><b>Jesse</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Jesse-Cameron" title="Code">💻</a> <a href="#content-Jesse-Cameron" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/MrFroop"><img src="https://avatars3.githubusercontent.com/u/196700?v=4" width="100px;" alt=""/><br /><sub><b>Fredrik Jambrén</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=MrFroop" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/petemcfarlane"><img src="https://avatars3.githubusercontent.com/u/3472717?v=4" width="100px;" alt=""/><br /><sub><b>Pete McFarlane</b></sub></a><br /><a href="#content-petemcfarlane" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/nkanderson"><img src="https://avatars0.githubusercontent.com/u/4128825?v=4" width="100px;" alt=""/><br /><sub><b>nkanderson</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=nkanderson" title="Code">💻</a> <a href="#content-nkanderson" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/ajaxm"><img src="https://avatars0.githubusercontent.com/u/13360138?v=4" width="100px;" alt=""/><br /><sub><b>Ajax M</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ajaxm" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://dylnuge.com"><img src="https://avatars2.githubusercontent.com/u/118624?v=4" width="100px;" alt=""/><br /><sub><b>Dylan Nugent</b></sub></a><br /><a href="#content-Dylnuge" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/vyaslav"><img src="https://avatars0.githubusercontent.com/u/1385427?v=4" width="100px;" alt=""/><br /><sub><b>vyaslav</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=vyaslav" title="Code">💻</a> <a href="#content-vyaslav" title="Content">🖋</a></td>
+    <td align="center"><a href="https://join.sfxd.org"><img src="https://avatars1.githubusercontent.com/u/17297466?v=4" width="100px;" alt=""/><br /><sub><b>George</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=gdoenlen" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/nyxtom"><img src="https://avatars2.githubusercontent.com/u/222763?v=4" width="100px;" alt=""/><br /><sub><b>Thomas Holloway</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=nyxtom" title="Code">💻</a> <a href="#content-nyxtom" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/workingjubilee"><img src="https://avatars1.githubusercontent.com/u/46493976?v=4" width="100px;" alt=""/><br /><sub><b>Jubilee</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=workingjubilee" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/WofWca"><img src="https://avatars1.githubusercontent.com/u/39462442?v=4" width="100px;" alt=""/><br /><sub><b>WofWca</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=WofWca" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/jrvidal"><img src="https://avatars0.githubusercontent.com/u/1636604?v=4" width="100px;" alt=""/><br /><sub><b>Roberto Vidal</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=jrvidal" title="Code">💻</a> <a href="https://github.com/rust-lang/rustlings/commits?author=jrvidal" title="Documentation">📖</a> <a href="#ideas-jrvidal" title="Ideas, Planning, & Feedback">🤔</a> <a href="#maintenance-jrvidal" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="https://github.com/jensim"><img src="https://avatars0.githubusercontent.com/u/3663856?v=4" width="100px;" alt=""/><br /><sub><b>Jens</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=jensim" title="Documentation">📖</a></td>
+    <td align="center"><a href="http://rahatah.me/d"><img src="https://avatars3.githubusercontent.com/u/3174006?v=4" width="100px;" alt=""/><br /><sub><b>Rahat Ahmed</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=rahatarmanahmed" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/AbdouSeck"><img src="https://avatars2.githubusercontent.com/u/6490055?v=4" width="100px;" alt=""/><br /><sub><b>Abdou Seck</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=AbdouSeck" title="Code">💻</a> <a href="#content-AbdouSeck" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/pulls?q=is%3Apr+reviewed-by%3AAbdouSeck" title="Reviewed Pull Requests">👀</a></td>
+    <td align="center"><a href="https://codehearts.com"><img src="https://avatars0.githubusercontent.com/u/2885412?v=4" width="100px;" alt=""/><br /><sub><b>Katie</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=codehearts" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/Socratides"><img src="https://avatars3.githubusercontent.com/u/27732983?v=4" width="100px;" alt=""/><br /><sub><b>Socrates</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Socratides" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/gnodarse"><img src="https://avatars3.githubusercontent.com/u/46761795?v=4" width="100px;" alt=""/><br /><sub><b>gnodarse</b></sub></a><br /><a href="#content-gnodarse" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/harrisonmetz"><img src="https://avatars1.githubusercontent.com/u/7883408?v=4" width="100px;" alt=""/><br /><sub><b>Harrison Metzger</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=harrisonmetz" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/TorbenJ"><img src="https://avatars2.githubusercontent.com/u/9077102?v=4" width="100px;" alt=""/><br /><sub><b>Torben Jonas</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=TorbenJ" title="Code">💻</a> <a href="#content-TorbenJ" title="Content">🖋</a></td>
+    <td align="center"><a href="http://paulbissex.com/"><img src="https://avatars0.githubusercontent.com/u/641?v=4" width="100px;" alt=""/><br /><sub><b>Paul Bissex</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=pbx" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/sjmann"><img src="https://avatars0.githubusercontent.com/u/6589896?v=4" width="100px;" alt=""/><br /><sub><b>Steven Mann</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sjmann" title="Code">💻</a> <a href="#content-sjmann" title="Content">🖋</a></td>
+    <td align="center"><a href="https://smmdb.net/"><img src="https://avatars2.githubusercontent.com/u/5855071?v=4" width="100px;" alt=""/><br /><sub><b>Mario Reder</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Tarnadas" title="Code">💻</a> <a href="#content-Tarnadas" title="Content">🖋</a></td>
+    <td align="center"><a href="https://keybase.io/skim"><img src="https://avatars0.githubusercontent.com/u/47347?v=4" width="100px;" alt=""/><br /><sub><b>skim</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sl4m" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/sanjaykdragon"><img src="https://avatars1.githubusercontent.com/u/10261698?v=4" width="100px;" alt=""/><br /><sub><b>Sanjay K</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sanjaykdragon" title="Code">💻</a> <a href="#content-sanjaykdragon" title="Content">🖋</a></td>
+    <td align="center"><a href="http://www.rohanjain.in"><img src="https://avatars1.githubusercontent.com/u/343499?v=4" width="100px;" alt=""/><br /><sub><b>Rohan Jain</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=crodjer" title="Code">💻</a></td>
+    <td align="center"><a href="https://www.saidaspen.se"><img src="https://avatars1.githubusercontent.com/u/7727687?v=4" width="100px;" alt=""/><br /><sub><b>Said Aspen</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=saidaspen" title="Code">💻</a> <a href="#content-saidaspen" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/uce"><img src="https://avatars3.githubusercontent.com/u/1756620?v=4" width="100px;" alt=""/><br /><sub><b>Ufuk Celebi</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=uce" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/lebedevsergey"><img src="https://avatars2.githubusercontent.com/u/7325764?v=4" width="100px;" alt=""/><br /><sub><b>lebedevsergey</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=lebedevsergey" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/avrong"><img src="https://avatars2.githubusercontent.com/u/6342851?v=4" width="100px;" alt=""/><br /><sub><b>Aleksei Trifonov</b></sub></a><br /><a href="#content-avrong" title="Content">🖋</a></td>
+    <td align="center"><a href="https://drn.ie"><img src="https://avatars2.githubusercontent.com/u/411136?v=4" width="100px;" alt=""/><br /><sub><b>Darren Meehan</b></sub></a><br /><a href="#content-Darrenmeehan" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/jihchi"><img src="https://avatars1.githubusercontent.com/u/87983?v=4" width="100px;" alt=""/><br /><sub><b>Jihchi Lee</b></sub></a><br /><a href="#content-jihchi" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/bertonha"><img src="https://avatars3.githubusercontent.com/u/1225902?v=4" width="100px;" alt=""/><br /><sub><b>Christofer Bertonha</b></sub></a><br /><a href="#content-bertonha" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/apatniv"><img src="https://avatars2.githubusercontent.com/u/22565917?v=4" width="100px;" alt=""/><br /><sub><b>Vivek Bharath Akupatni</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=apatniv" title="Code">💻</a> <a href="https://github.com/rust-lang/rustlings/commits?author=apatniv" title="Tests">⚠️</a></td>
+    <td align="center"><a href="https://github.com/DiD92"><img src="https://avatars3.githubusercontent.com/u/6002416?v=4" width="100px;" alt=""/><br /><sub><b>Dídac Sementé Fernández</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=DiD92" title="Code">💻</a> <a href="#content-DiD92" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/wrobstory"><img src="https://avatars3.githubusercontent.com/u/2601457?v=4" width="100px;" alt=""/><br /><sub><b>Rob Story</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=wrobstory" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/siobhanjacobson"><img src="https://avatars2.githubusercontent.com/u/28983835?v=4" width="100px;" alt=""/><br /><sub><b>Siobhan Jacobson</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=siobhanjacobson" title="Code">💻</a></td>
+    <td align="center"><a href="https://www.linkedin.com/in/evancarroll/"><img src="https://avatars2.githubusercontent.com/u/19922?v=4" width="100px;" alt=""/><br /><sub><b>Evan Carroll</b></sub></a><br /><a href="#content-EvanCarroll" title="Content">🖋</a></td>
+    <td align="center"><a href="http://www.jawaadmahmood.com"><img src="https://avatars3.githubusercontent.com/u/95606?v=4" width="100px;" alt=""/><br /><sub><b>Jawaad Mahmood</b></sub></a><br /><a href="#content-jmahmood" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/GaurangTandon"><img src="https://avatars1.githubusercontent.com/u/6308683?v=4" width="100px;" alt=""/><br /><sub><b>Gaurang Tandon</b></sub></a><br /><a href="#content-GaurangTandon" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/dev-cyprium"><img src="https://avatars1.githubusercontent.com/u/6002628?v=4" width="100px;" alt=""/><br /><sub><b>Stefan Kupresak</b></sub></a><br /><a href="#content-dev-cyprium" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/greg-el"><img src="https://avatars3.githubusercontent.com/u/45019882?v=4" width="100px;" alt=""/><br /><sub><b>Greg Leonard</b></sub></a><br /><a href="#content-greg-el" title="Content">🖋</a></td>
+    <td align="center"><a href="https://ryanpcmcquen.org"><img src="https://avatars3.githubusercontent.com/u/772937?v=4" width="100px;" alt=""/><br /><sub><b>Ryan McQuen</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ryanpcmcquen" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/AnnikaCodes"><img src="https://avatars3.githubusercontent.com/u/56906084?v=4" width="100px;" alt=""/><br /><sub><b>Annika</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/pulls?q=is%3Apr+reviewed-by%3AAnnikaCodes" title="Reviewed Pull Requests">👀</a></td>
+    <td align="center"><a href="https://darnuria.eu"><img src="https://avatars1.githubusercontent.com/u/2827553?v=4" width="100px;" alt=""/><br /><sub><b>Axel Viala</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=darnuria" title="Code">💻</a></td>
+    <td align="center"><a href="https://sazid.github.io"><img src="https://avatars1.githubusercontent.com/u/2370167?v=4" width="100px;" alt=""/><br /><sub><b>Mohammed Sazid Al Rashid</b></sub></a><br /><a href="#content-sazid" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/commits?author=sazid" title="Code">💻</a></td>
+    <td align="center"><a href="https://codingthemsoftly.com"><img src="https://avatars1.githubusercontent.com/u/17479099?v=4" width="100px;" alt=""/><br /><sub><b>Caleb Webber</b></sub></a><br /><a href="#maintenance-seeplusplus" title="Maintenance">🚧</a></td>
+  </tr>
+</table>
+
+<!-- markdownlint-enable -->
+<!-- prettier-ignore-end -->
+<!-- ALL-CONTRIBUTORS-LIST:END -->
+
+This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
--- a/buildkite.yml
+++ b/buildkite.yml
@@ -0,0 +1,5 @@
+steps:
+  - label: "Test with stable"
+    command: rustup run stable cargo test
+  - label: "Test with beta"
+    command: rustup run beta cargo test
--- a/exercises/clippy/README.md
+++ b/exercises/clippy/README.md
@@ -0,0 +1,8 @@
+### Clippy
+
+The Clippy tool is a collection of lints to analyze your code so you can catch common mistakes and improve your Rust code.
+
+If you used the installation script for Rustlings, Clippy should be already installed.
+If not you can install it manually via `rustup component add clippy`.
+
+For more information about Clippy lints, please see [their documentation page](https://rust-lang.github.io/rust-clippy/master/).
--- a/exercises/clippy/clippy1.rs
+++ b/exercises/clippy/clippy1.rs
@@ -0,0 +1,17 @@
+// clippy1.rs
+// The Clippy tool is a collection of lints to analyze your code
+// so you can catch common mistakes and improve your Rust code.
+//
+// For these exercises the code will fail to compile when there are clippy warnings
+// check clippy's suggestions from the output to solve the exercise.
+// Execute `rustlings hint clippy1` for hints :)
+
+// I AM NOT DONE
+
+fn main() {
+    let x = 1.2331f64;
+    let y = 1.2332f64;
+    if y != x {
+        println!("Success!");
+    }
+}
--- a/exercises/clippy/clippy2.rs
+++ b/exercises/clippy/clippy2.rs
@@ -0,0 +1,13 @@
+// clippy2.rs
+// Make me compile! Execute `rustlings hint clippy2` for hints :)
+
+// I AM NOT DONE
+
+fn main() {
+    let mut res = 42;
+    let option = Some(12);
+    for x in option {
+        res += x;
+    }
+    println!("{}", res);
+}
--- a/exercises/collections/README.md
+++ b/exercises/collections/README.md
@@ -0,0 +1,20 @@
+### Collections
+
+Rust’s standard library includes a number of very useful data
+structures called collections. Most other data types represent one
+specific value, but collections can contain multiple values. Unlike
+the built-in array and tuple types, the data these collections point
+to is stored on the heap, which means the amount of data does not need
+to be known at compile time and can grow or shrink as the program
+runs.
+
+This exercise will get you familiar with two fundamental data
+structures that are used very often in Rust programs:
+
+* A *vector* allows you to store a variable number of values next to
+  each other.
+* A *hash map* allows you to associate a value with a particular key.
+  You may also know this by the names *map* in C++, *dictionary* in
+  Python or an *associative array* in other languages.
+
+[Rust book chapter](https://doc.rust-lang.org/stable/book/ch08-01-vectors.html)
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -0,0 +1,46 @@
+// hashmap1.rs
+// A basket of fruits in the form of a hash map needs to be defined.
+// The key represents the name of the fruit and the value represents
+// how many of that particular fruit is in the basket. You have to put
+// at least three different types of fruits (e.g apple, banana, mango)
+// in the basket and the total count of all the fruits should be at
+// least five.
+//
+// Make me compile and pass the tests!
+//
+// Execute the command `rustlings hint collections3` if you need
+// hints.
+
+// I AM NOT DONE
+
+use std::collections::HashMap;
+
+fn fruit_basket() -> HashMap<String, u32> {
+    let mut basket = // TODO: declare your hash map here.
+
+    // Two bananas are already given for you :)
+    basket.insert(String::from("banana"), 2);
+
+    // TODO: Put more fruits in your basket here.
+
+    basket
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn at_least_three_types_of_fruits() {
+        let basket = fruit_basket();
+        assert!(basket.len() >= 3);
+    }
+
+    #[test]
+    fn at_least_five_fruits() {
+        let basket = fruit_basket();
+        assert!(basket
+            .values()
+            .sum::<u32>() >= 5);
+    }
+}
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -0,0 +1,83 @@
+// hashmap2.rs
+
+// A basket of fruits in the form of a hash map is given. The key
+// represents the name of the fruit and the value represents how many
+// of that particular fruit is in the basket. You have to put *MORE
+// THAN 11* fruits in the basket. Three types of fruits - Apple (4),
+// Mango (2) and Lichi (5) are already given in the basket. You are
+// not allowed to insert any more of these fruits!
+//
+// Make me pass the tests!
+//
+// Execute the command `rustlings hint collections4` if you need
+// hints.
+
+// I AM NOT DONE
+
+use std::collections::HashMap;
+
+#[derive(Hash, PartialEq, Eq)]
+enum Fruit {
+    Apple,
+    Banana,
+    Mango,
+    Lichi,
+    Pineapple,
+}
+
+fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
+    let fruit_kinds = vec![
+        Fruit::Apple,
+        Fruit::Banana,
+        Fruit::Mango,
+        Fruit::Lichi,
+        Fruit::Pineapple,
+    ];
+
+    for fruit in fruit_kinds {
+        // TODO: Put new fruits if not already present. Note that you
+        // are not allowed to put any type of fruit that's already
+        // present!
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn get_fruit_basket() -> HashMap<Fruit, u32> {
+        let mut basket = HashMap::<Fruit, u32>::new();
+        basket.insert(Fruit::Apple, 4);
+        basket.insert(Fruit::Mango, 2);
+        basket.insert(Fruit::Lichi, 5);
+
+        basket
+    }
+
+    #[test]
+    fn test_given_fruits_are_not_modified() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        assert_eq!(*basket.get(&Fruit::Apple).unwrap(), 4);
+        assert_eq!(*basket.get(&Fruit::Mango).unwrap(), 2);
+        assert_eq!(*basket.get(&Fruit::Lichi).unwrap(), 5);
+    }
+
+    #[test]
+    fn at_least_five_types_of_fruits() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        let count_fruit_kinds = basket.len();
+        assert!(count_fruit_kinds == 5);
+    }
+
+    #[test]
+    fn greater_than_eleven_fruits() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        let count = basket
+            .values()
+            .sum::<u32>();
+        assert!(count > 11);
+    }
+}
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -0,0 +1,25 @@
+// vec1.rs
+// Your task is to create a `Vec` which holds the exact same elements
+// as in the array `a`.
+// Make me compile and pass the test!
+// Execute the command `rustlings hint collections1` if you need hints.
+
+// I AM NOT DONE
+
+fn array_and_vec() -> ([i32; 4], Vec<i32>) {
+    let a = [10, 20, 30, 40]; // a plain array
+    let v = // TODO: declare your vector here with the macro for vectors
+
+    (a, v)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_array_and_vec_similarity() {
+        let (a, v) = array_and_vec();
+        assert!(a.iter().zip(v.iter()).all(|(x, y)| x == y));
+    }
+}
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -0,0 +1,38 @@
+// vec2.rs
+// A Vec of even numbers is given. Your task is to complete the loop
+// so that each number in the Vec is multiplied by 2.
+//
+// Make me pass the test!
+//
+// Execute the command `rustlings hint collections2` if you need
+// hints.
+
+// I AM NOT DONE
+
+fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
+    for i in v.iter_mut() {
+        // TODO: Fill this up so that each element in the Vec `v` is
+        // multiplied by 2.
+    }
+
+    // At this point, `v` should be equal to [4, 8, 12, 16, 20].
+    v
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_vec_loop() {
+        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
+        let ans = vec_loop(v.clone());
+
+        assert_eq!(
+            ans,
+            v.iter()
+                .map(|x| x * 2)
+                .collect::<Vec<i32>>()
+        );
+    }
+}
--- a/exercises/conversions/README.md
+++ b/exercises/conversions/README.md
@@ -0,0 +1,20 @@
+### Type conversions
+
+
+Rust offers a multitude of ways to convert a value of a given type into another type.
+
+The simplest form of type conversion is a type cast expression. It is denoted with the binary operator `as`. For instance, `println!("{}", 1 + 1.0);` would not compile, since `1` is an integer while `1.0` is a float. However, `println!("{}", 1 as f32 + 1.0)` should compile. The exercise [`using_as`](using_as.rs) tries to cover this.
+
+Rust also offers traits that facilitate type conversions upon implementation. These traits can be found under the [`convert`](https://doc.rust-lang.org/std/convert/index.html) module.
+The traits are the following:
+- `From` and `Into` covered in [`from_into`](from_into.rs)
+- `TryFrom` and `TryInto` covered in [`try_from_into`](try_from_into.rs)
+- `AsRef` and `AsMut` covered in [`as_ref_mut`](as_ref_mut.rs)
+
+Furthermore, the `std::str` module offers a trait called [`FromStr`](https://doc.rust-lang.org/std/str/trait.FromStr.html) which helps with converting strings into target types via the `parse` method on strings. If properly implemented for a given type `Person`, then `let p: Person = "Mark,20".parse().unwrap()` should both compile and run without panicking.
+
+These should be the main ways ***within the standard library*** to convert data into your desired types.
+
+#### Book Sections
+
+These are not directly covered in the book, but the standard library has great documentation for [conversions here](https://doc.rust-lang.org/std/convert/index.html). The `FromStr` trait is also covered [here](https://doc.rust-lang.org/std/str/trait.FromStr.html).
--- a/exercises/conversions/as_ref_mut.rs
+++ b/exercises/conversions/as_ref_mut.rs
@@ -0,0 +1,52 @@
+// AsRef and AsMut allow for cheap reference-to-reference conversions.
+// Read more about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html
+// and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
+
+// I AM NOT DONE
+
+// Obtain the number of bytes (not characters) in the given argument
+// Add the AsRef trait appropriately as a trait bound
+fn byte_counter<T>(arg: T) -> usize {
+    arg.as_ref().as_bytes().len()
+}
+
+// Obtain the number of characters (not bytes) in the given argument
+// Add the AsRef trait appropriately as a trait bound
+fn char_counter<T>(arg: T) -> usize {
+    arg.as_ref().chars().count()
+}
+
+fn main() {
+    let s = "Café au lait";
+    println!("{}", char_counter(s));
+    println!("{}", byte_counter(s));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn different_counts() {
+        let s = "Café au lait";
+        assert_ne!(char_counter(s), byte_counter(s));
+    }
+
+    #[test]
+    fn same_counts() {
+        let s = "Cafe au lait";
+        assert_eq!(char_counter(s), byte_counter(s));
+    }
+
+    #[test]
+    fn different_counts_using_string() {
+        let s = String::from("Café au lait");
+        assert_ne!(char_counter(s.clone()), byte_counter(s));
+    }
+
+    #[test]
+    fn same_counts_using_string() {
+        let s = String::from("Cafe au lait");
+        assert_eq!(char_counter(s.clone()), byte_counter(s));
+    }
+}
--- a/exercises/conversions/from_into.rs
+++ b/exercises/conversions/from_into.rs
@@ -0,0 +1,118 @@
+// The From trait is used for value-to-value conversions.
+// If From is implemented correctly for a type, the Into trait should work conversely.
+// You can read more about it at https://doc.rust-lang.org/std/convert/trait.From.html
+#[derive(Debug)]
+struct Person {
+    name: String,
+    age: usize,
+}
+
+// We implement the Default trait to use it as a fallback
+// when the provided string is not convertible into a Person object
+impl Default for Person {
+    fn default() -> Person {
+        Person {
+            name: String::from("John"),
+            age: 30,
+        }
+    }
+}
+
+// Your task is to complete this implementation
+// in order for the line `let p = Person::from("Mark,20")` to compile
+// Please note that you'll need to parse the age component into a `usize`
+// with something like `"4".parse::<usize>()`. The outcome of this needs to
+// be handled appropriately.
+//
+// Steps:
+// 1. If the length of the provided string is 0, then return the default of Person
+// 2. Split the given string on the commas present in it
+// 3. Extract the first element from the split operation and use it as the name
+// 4. If the name is empty, then return the default of Person
+// 5. Extract the other element from the split operation and parse it into a `usize` as the age
+// If while parsing the age, something goes wrong, then return the default of Person
+// Otherwise, then return an instantiated Person object with the results
+
+// I AM NOT DONE
+
+impl From<&str> for Person {
+    fn from(s: &str) -> Person {
+    }
+}
+
+fn main() {
+    // Use the `from` function
+    let p1 = Person::from("Mark,20");
+    // Since From is implemented for Person, we should be able to use Into
+    let p2: Person = "Gerald,70".into();
+    println!("{:?}", p1);
+    println!("{:?}", p2);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_default() {
+        // Test that the default person is 30 year old John
+        let dp = Person::default();
+        assert_eq!(dp.name, "John");
+        assert_eq!(dp.age, 30);
+    }
+    #[test]
+    fn test_bad_convert() {
+        // Test that John is returned when bad string is provided
+        let p = Person::from("");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+    #[test]
+    fn test_good_convert() {
+        // Test that "Mark,20" works
+        let p = Person::from("Mark,20");
+        assert_eq!(p.name, "Mark");
+        assert_eq!(p.age, 20);
+    }
+    #[test]
+    fn test_bad_age() {
+        // Test that "Mark,twenty" will return the default person due to an error in parsing age
+        let p = Person::from("Mark,twenty");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_comma_and_age() {
+        let p: Person = Person::from("Mark");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_age() {
+        let p: Person = Person::from("Mark,");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name() {
+        let p: Person = Person::from(",1");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name_and_age() {
+        let p: Person = Person::from(",");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name_and_invalid_age() {
+        let p: Person = Person::from(",one");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+}
--- a/exercises/conversions/from_str.rs
+++ b/exercises/conversions/from_str.rs
@@ -0,0 +1,85 @@
+// This does practically the same thing that TryFrom<&str> does.
+// Additionally, upon implementing FromStr, you can use the `parse` method
+// on strings to generate an object of the implementor type.
+// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
+use std::str::FromStr;
+
+#[derive(Debug)]
+struct Person {
+    name: String,
+    age: usize,
+}
+
+// I AM NOT DONE
+// Steps:
+// 1. If the length of the provided string is 0, then return an error
+// 2. Split the given string on the commas present in it
+// 3. Extract the first element from the split operation and use it as the name
+// 4. If the name is empty, then return an error
+// 5. Extract the other element from the split operation and parse it into a `usize` as the age
+//    with something like `"4".parse::<usize>()`.
+// If while parsing the age, something goes wrong, then return an error
+// Otherwise, then return a Result of a Person object
+impl FromStr for Person {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Person, Self::Err> {
+    }
+}
+
+fn main() {
+    let p = "Mark,20".parse::<Person>().unwrap();
+    println!("{:?}", p);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn empty_input() {
+        assert!("".parse::<Person>().is_err());
+    }
+    #[test]
+    fn good_input() {
+        let p = "John,32".parse::<Person>();
+        assert!(p.is_ok());
+        let p = p.unwrap();
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 32);
+    }
+    #[test]
+    #[should_panic]
+    fn missing_age() {
+        "John,".parse::<Person>().unwrap();
+    }
+
+    #[test]
+    #[should_panic]
+    fn invalid_age() {
+        "John,twenty".parse::<Person>().unwrap();
+    }
+
+    #[test]
+    #[should_panic]
+    fn missing_comma_and_age() {
+        "John".parse::<Person>().unwrap();
+    }
+
+    #[test]
+    #[should_panic]
+    fn missing_name() {
+        ",1".parse::<Person>().unwrap();
+    }
+
+    #[test]
+    #[should_panic]
+    fn missing_name_and_age() {
+        ",".parse::<Person>().unwrap();
+    }
+
+    #[test]
+    #[should_panic]
+    fn missing_name_and_invalid_age() {
+        ",one".parse::<Person>().unwrap();
+    }
+}
--- a/exercises/conversions/try_from_into.rs
+++ b/exercises/conversions/try_from_into.rs
@@ -0,0 +1,155 @@
+// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
+// Basically, this is the same as From. The main difference is that this should return a Result type
+// instead of the target type itself.
+// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
+use std::convert::{TryFrom, TryInto};
+
+#[derive(Debug, PartialEq)]
+struct Color {
+    red: u8,
+    green: u8,
+    blue: u8,
+}
+
+// I AM NOT DONE
+
+// Your task is to complete this implementation
+// and return an Ok result of inner type Color.
+// You need create implementation for a tuple of three integer,
+// an array of three integer and slice of integer.
+//
+// Note, that implementation for tuple and array will be checked at compile-time,
+// but slice implementation need check slice length!
+// Also note, that chunk of correct rgb color must be integer in range 0..=255.
+
+// Tuple implementation
+impl TryFrom<(i16, i16, i16)> for Color {
+    type Error = String;
+    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {}
+}
+
+// Array implementation
+impl TryFrom<[i16; 3]> for Color {
+    type Error = String;
+    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {}
+}
+
+// Slice implementation
+impl TryFrom<&[i16]> for Color {
+    type Error = String;
+    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
+}
+
+fn main() {
+    // Use the `from` function
+    let c1 = Color::try_from((183, 65, 14));
+    println!("{:?}", c1);
+
+    // Since From is implemented for Color, we should be able to use Into
+    let c2: Result<Color, _> = [183, 65, 14].try_into();
+    println!("{:?}", c2);
+
+    let v = vec![183, 65, 14];
+    // With slice we should use `from` function
+    let c3 = Color::try_from(&v[..]);
+    println!("{:?}", c3);
+    // or take slice within round brackets and use Into
+    let c4: Result<Color, _> = (&v[..]).try_into();
+    println!("{:?}", c4);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_tuple_out_of_range_positive() {
+        assert!(Color::try_from((256, 1000, 10000)).is_err());
+    }
+    #[test]
+    fn test_tuple_out_of_range_negative() {
+        assert!(Color::try_from((-1, -10, -256)).is_err());
+    }
+    #[test]
+    fn test_tuple_sum() {
+        assert!(Color::try_from((-1, 255, 255)).is_err());
+    }
+    #[test]
+    fn test_tuple_correct() {
+        let c: Result<Color, String> = (183, 65, 14).try_into();
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
+    }
+    #[test]
+    fn test_array_out_of_range_positive() {
+        let c: Color = [1000, 10000, 256].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    fn test_array_out_of_range_negative() {
+        let c: Color = [-10, -256, -1].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    fn test_array_sum() {
+        let c: Color = [-1, 255, 255].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    #[test]
+    fn test_array_correct() {
+        let c: Result<Color, String> = [183, 65, 14].try_into();
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
+    }
+    #[test]
+    fn test_slice_out_of_range_positive() {
+        let arr = [10000, 256, 1000];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_out_of_range_negative() {
+        let arr = [-256, -1, -10];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_sum() {
+        let arr = [-1, 255, 255];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_correct() {
+        let v = vec![183, 65, 14];
+        let c: Result<Color, String> = Color::try_from(&v[..]);
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
+    }
+    #[test]
+    fn test_slice_excess_length() {
+        let v = vec![0, 0, 0, 0];
+        assert!(Color::try_from(&v[..]).is_err());
+    }
+    #[test]
+    fn test_slice_insufficient_length() {
+        let v = vec![0, 0];
+        assert!(Color::try_from(&v[..]).is_err());
+    }
+}
--- a/exercises/conversions/using_as.rs
+++ b/exercises/conversions/using_as.rs
@@ -0,0 +1,28 @@
+// Type casting in Rust is done via the usage of the `as` operator.
+// Please note that the `as` operator is not only used when type casting.
+// It also helps with renaming imports.
+//
+// The goal is to make sure that the division does not fail to compile
+// and returns the proper type.
+
+// I AM NOT DONE
+
+fn average(values: &[f64]) -> f64 {
+    let total = values.iter().fold(0.0, |a, b| a + b);
+    total / values.len()
+}
+
+fn main() {
+    let values = [3.5, 0.3, 13.0, 11.7];
+    println!("{}", average(&values));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn returns_proper_type_and_value() {
+        assert_eq!(average(&[3.5, 0.3, 13.0, 11.7]), 7.125);
+    }
+}
--- a/exercises/enums/README.md
+++ b/exercises/enums/README.md
@@ -1,7 +1,10 @@
 ### Enums

-Rust allows you to define a type called `enums` which allow you to enumerate possible values. In combination with enums, we have the concept of `pattern matching` in Rust, which makes it easy to run different code for different values of an enumeration. Enums, while available in many languages, Rust's enums are most similar to `algebraic data types` in functional languages, such as F#, OCaml, and Haskell.
+Rust allows you to define types called "enums" which enumerate possible values.
+Enums are a feature in many languages, but their capabilities differ in each language. Rust’s enums are most similar to algebraic data types in functional languages, such as F#, OCaml, and Haskell.
+Useful in combination with enums is Rust's "pattern matching" facility, which makes it easy to run different code for different values of an enumeration.

 #### Book Sections

 - [Enums](https://doc.rust-lang.org/book/ch06-00-enums.html)
+- [Pattern syntax](https://doc.rust-lang.org/book/ch18-03-pattern-syntax.html)
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -16,10 +16,10 @@ impl Message {

 fn main() {
    let messages = [
-        Message::Move{ x: 10, y: 30 },
+        Message::Move { x: 10, y: 30 },
        Message::Echo(String::from("hello world")),
        Message::ChangeColor(200, 255, 255),
-        Message::Quit
+        Message::Quit,
    ];

    for message in &messages {
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -9,13 +9,13 @@ enum Message {

 struct Point {
    x: u8,
-    y: u8
+    y: u8,
 }

 struct State {
    color: (u8, u8, u8),
    position: Point,
-    quit: bool
+    quit: bool,
 }

 impl State {
@@ -46,14 +46,14 @@ mod tests {

    #[test]
    fn test_match_message_call() {
-        let mut state = State{
+        let mut state = State {
            quit: false,
-            position: Point{ x: 0, y: 0 },
-            color: (0, 0, 0)
+            position: Point { x: 0, y: 0 },
+            color: (0, 0, 0),
        };
-        state.process(Message::ChangeColor(255, 0, 255));
+        state.process(Message::ChangeColor((255, 0, 255)));
        state.process(Message::Echo(String::from("hello world")));
-        state.process(Message::Move{ x: 10, y: 15 });
+        state.process(Message::Move(Point { x: 10, y: 15 }));
        state.process(Message::Quit);

        assert_eq!(state.color, (255, 0, 255));
@@ -61,5 +61,4 @@ mod tests {
        assert_eq!(state.position.y, 15);
        assert_eq!(state.quit, true);
    }
-
 }
--- a/exercises/error_handling/README.md
+++ b/exercises/error_handling/README.md
@@ -1,5 +1,5 @@
 For this exercise check out the sections:
- [Error Handling](https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html) 
- [Generics](https://doc.rust-lang.org/book/ch10-01-syntax.html) 
+- [Error Handling](https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html)
+- [Generics](https://doc.rust-lang.org/book/ch10-01-syntax.html)

 of the Rust Book.
--- a/exercises/error_handling/errorsn.rs
+++ b/exercises/error_handling/errorsn.rs
@@ -2,8 +2,10 @@
 // This is a bigger error exercise than the previous ones!
 // You can do it! :)
 //
-// Edit the `read_and_validate` function so that it compiles and
-// passes the tests... so many things could go wrong!
+// Edit the `read_and_validate` function ONLY. Don't create any Errors
+// that do not already exist.
+//
+// So many things could go wrong!
 //
 // - Reading from stdin could produce an io::Error
 // - Parsing the input could produce a num::ParseIntError
@@ -30,6 +32,10 @@ fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger,
    answer
 }

+//
+// Nothing below this needs to be modified
+//
+
 // This is a test helper function that turns a &str into a BufReader.
 fn test_with_str(s: &str) -> Result<PositiveNonzeroInteger, Box<dyn error::Error>> {
    let mut b = io::BufReader::new(s.as_bytes());
@@ -100,15 +106,12 @@ enum CreationError {

 impl fmt::Display for CreationError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str((self as &dyn error::Error).description())
+        let description = match *self {
+            CreationError::Negative => "Number is negative",
+            CreationError::Zero => "Number is zero",
+        };
+        f.write_str(description)
    }
 }

-impl error::Error for CreationError {
-    fn description(&self) -> &str {
-        match *self {
-            CreationError::Negative => "Negative",
-            CreationError::Zero => "Zero",
-        }
-    }
-}
+impl error::Error for CreationError {}
--- a/exercises/error_handling/option1.rs
+++ b/exercises/error_handling/option1.rs
@@ -1,31 +0,0 @@
-// option1.rs
-// This example panics because the second time it calls `pop`, the `vec`
-// is empty, so `pop` returns `None`, and `unwrap` panics if it's called
-// on `None`. Handle this in a more graceful way than calling `unwrap`!
-// Execute `rustlings hint option1` for hints :)
-
-// I AM NOT DONE
-
-pub fn pop_too_much() -> bool {
-    let mut list = vec![3];
-
-    let last = list.pop().unwrap();
-    println!("The last item in the list is {:?}", last);
-
-    let second_to_last = list.pop().unwrap();
-    println!(
-        "The second-to-last item in the list is {:?}",
-        second_to_last
-    );
-    true
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn should_not_panic() {
-        assert!(pop_too_much());
-    }
-}
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -2,7 +2,7 @@
 // Make me compile! Execute `rustlings hint functions4` for hints :)

 // This store is having a sale where if the price is an even number, you get
-// 10 (money unit) off, but if it's an odd number, it's 3 (money unit) less.
+// 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off.

 // I AM NOT DONE

--- a/exercises/generics/README.md
+++ b/exercises/generics/README.md
@@ -0,0 +1,7 @@
+### Generics
+
+In this section you'll learn about saving yourself many lines of code with generics!
+
+### Book Sections
+
+- [Generic Data Types](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html)
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -0,0 +1,9 @@
+// This shopping list program isn't compiling!
+// Use your knowledge of generics to fix it.
+
+// I AM NOT DONE
+
+fn main() {
+    let mut shopping_list: Vec<?> = Vec::new();
+    shopping_list.push("milk");
+}
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -0,0 +1,29 @@
+// This powerful wrapper provides the ability to store a positive integer value.
+// Rewrite it using generics so that it supports wrapping ANY type.
+
+// I AM NOT DONE
+
+struct Wrapper {
+    value: u32,
+}
+
+impl Wrapper {
+    pub fn new(value: u32) -> Self {
+        Wrapper { value }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn store_u32_in_wrapper() {
+        assert_eq!(Wrapper::new(42).value, 42);
+    }
+
+    #[test]
+    fn store_str_in_wrapper() {
+        assert_eq!(Wrapper::new("Foo").value, "Foo");
+    }
+}
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -0,0 +1,58 @@
+// An imaginary magical school has a new report card generation system written in Rust!
+// Currently the system only supports creating report cards where the student's grade
+// is represented numerically (e.g. 1.0 -> 5.5).
+// However, the school also issues alphabetical grades (A+ -> F-) and needs
+// to be able to print both types of report card!
+
+// Make the necessary code changes in the struct ReportCard and the impl block
+// to support alphabetical report cards. Change the Grade in the second test to "A+"
+// to show that your changes allow alphabetical grades.
+
+// Execute 'rustlings hint generics3' for hints!
+
+// I AM NOT DONE
+
+pub struct ReportCard {
+    pub grade: f32,
+    pub student_name: String,
+    pub student_age: u8,
+}
+
+impl ReportCard {
+    pub fn print(&self) -> String {
+        format!("{} ({}) - achieved a grade of {}",
+            &self.student_name, &self.student_age, &self.grade)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn generate_numeric_report_card() {
+        let report_card = ReportCard {
+            grade: 2.1,
+            student_name: "Tom Wriggle".to_string(),
+            student_age: 12,
+        };
+        assert_eq!(
+            report_card.print(),
+            "Tom Wriggle (12) - achieved a grade of 2.1"
+        );
+    }
+
+    #[test]
+    fn generate_alphabetic_report_card() {
+        // TODO: Make sure to change the grade here after you finish the exercise.
+        let report_card = ReportCard {
+            grade: 2.1,
+            student_name: "Gary Plotter".to_string(),
+            student_age: 11,
+        };
+        assert_eq!(
+            report_card.print(),
+            "Gary Plotter (11) - achieved a grade of A+"
+        );
+    }
+}
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -0,0 +1,36 @@
+// if2.rs
+
+// Step 1: Make me compile!
+// Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
+// Execute the command `rustlings hint if2` if you want a hint :)
+
+// I AM NOT DONE
+
+pub fn fizz_if_foo(fizzish: &str) -> &str {
+    if fizzish == "fizz" {
+        "foo"
+    } else {
+        1
+    }
+}
+
+// No test changes needed!
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn foo_for_fizz() {
+        assert_eq!(fizz_if_foo("fizz"), "foo")
+    }
+
+    #[test]
+    fn bar_for_fuzz() {
+        assert_eq!(fizz_if_foo("fuzz"), "bar")
+    }
+
+    #[test]
+    fn default_to_baz() {
+        assert_eq!(fizz_if_foo("literally anything"), "baz")
+    }
+}
--- a/exercises/macros/README.md
+++ b/exercises/macros/README.md
@@ -2,7 +2,7 @@

 Rust's macro system is very powerful, but also kind of difficult to wrap your
 head around. We're not going to teach you how to write your own fully-featured
-modules, instead we'll show you how to use and create them.
+macros. Instead, we'll show you how to use and create them.

 #### Book Sections

--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -1,5 +1,5 @@
 // move_semantics2.rs
-// Make me compile without changing line 10!
+// Make me compile without changing line 13!
 // Execute `rustlings hint move_semantics2` for hints :)

 // I AM NOT DONE
--- a/exercises/option/README.md
+++ b/exercises/option/README.md
@@ -0,0 +1,9 @@
+### Option
+
+#### Book Sections
+
+To learn about Option<T>, check out these links:
+
+- [Option Enum Format](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-enum-definitions)
+- [Option Module Documentation](https://doc.rust-lang.org/std/option/)
+- [Option Enum Documentation](https://doc.rust-lang.org/std/option/enum.Option.html)
--- a/exercises/option/option1.rs
+++ b/exercises/option/option1.rs
@@ -0,0 +1,23 @@
+// option1.rs
+// Make me compile! Execute `rustlings hint option1` for hints
+
+// I AM NOT DONE
+
+// you can modify anything EXCEPT for this function's sig
+fn print_number(maybe_number: Option<u16>) {
+    println!("printing: {}", maybe_number.unwrap());
+}
+
+fn main() {
+    print_number(13);
+    print_number(99);
+
+    let mut numbers: [Option<u16>; 5];
+    for iter in 0..5 {
+        let number_to_add: u16 = {
+            ((iter * 1235) + 2) / (4 * 16)
+        };
+
+        numbers[iter as usize] = number_to_add;
+    }
+}
--- a/exercises/option/option2.rs
+++ b/exercises/option/option2.rs
@@ -0,0 +1,25 @@
+// option2.rs
+// Make me compile! Execute `rustlings hint option2` for hints
+
+// I AM NOT DONE
+
+fn main() {
+    let optional_value = Some(String::from("rustlings"));
+    // TODO: Make this an if let statement whose value is "Some" type
+    value = optional_value {
+        println!("the value of optional value is: {}", value);
+    } else {
+        println!("The optional value doesn't contain anything!");
+    }
+
+    let mut optional_values_vec: Vec<Option<i8>> = Vec::new();
+    for x in 1..10 {
+        optional_values_vec.push(Some(x));
+    }
+
+    // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
+    // You can stack `Option<T>`'s into while let and if let
+    value = optional_values_vec.pop() {
+        println!("current value: {}", value);
+    }
+}
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -1,5 +1,5 @@
 // primitive_types3.rs
-// Create an array with at least 100 elements in it where the ??? is. 
+// Create an array with at least 100 elements in it where the ??? is.
 // Execute `rustlings hint primitive_types3` for hints!

 // I AM NOT DONE
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -1,11 +1,11 @@
 // primitive_types4.rs
-// Get a slice out of Array a where the ??? is so that the `if` statement
-// returns true. Execute `rustlings hint primitive_types4` for hints!!
+// Get a slice out of Array a where the ??? is so that the test passes.
+// Execute `rustlings hint primitive_types4` for hints!!

 // I AM NOT DONE

 #[test]
-fn main() {
+fn slice_out_of_array() {
    let a = [1, 2, 3, 4, 5];

    let nice_slice = ???
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -1,11 +1,16 @@
 // primitive_types6.rs
 // Use a tuple index to access the second element of `numbers`.
-// You can put this right into the `println!` where the ??? is.
+// You can put the expression for the second element where ??? is so that the test passes.
 // Execute `rustlings hint primitive_types6` for hints!

 // I AM NOT DONE

-fn main() {
+#[test]
+fn indexing_tuple() {
    let numbers = (1, 2, 3);
-    println!("The second number is {}", ???);
+    // Replace below ??? with the tuple indexing syntax.
+    let second = ???;
+
+    assert_eq!(2, second,
+        "This is not the 2nd number in the tuple!")
 }
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -1,9 +1,9 @@
-// test1.rs
-// This is a test for the following sections:
+// quiz1.rs
+// This is a quiz for the following sections:
 // - Variables
 // - Functions

-// Mary is buying apples. One apple usually costs 2 dollars, but if you buy
+// Mary is buying apples. One apple usually costs 2 Rustbucks, but if you buy
 // more than 40 at once, each apple only costs 1! Write a function that calculates
 // the price of an order of apples given the order amount. No hints this time!

--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -0,0 +1,30 @@
+// quiz2.rs
+// This is a quiz for the following sections:
+// - Strings
+
+// Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your
+// task is to call one of these two functions on each value depending on what
+// you think each value is. That is, add either `string_slice` or `string`
+// before the parentheses on each line. If you're right, it will compile!
+
+// I AM NOT DONE
+
+fn string_slice(arg: &str) {
+    println!("{}", arg);
+}
+fn string(arg: String) {
+    println!("{}", arg);
+}
+
+fn main() {
+    ???("blue");
+    ???("red".to_string());
+    ???(String::from("hi"));
+    ???("rust is fun!".to_owned());
+    ???("nice weather".into());
+    ???(format!("Interpolation {}", "Station"));
+    ???(&String::from("abc")[0..1]);
+    ???("  hello there ".trim());
+    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
+    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+}
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -1,8 +1,8 @@
-// test3.rs
-// This is a test for the following sections:
+// quiz3.rs
+// This is a quiz for the following sections:
 // - Tests

-// This test isn't testing our function -- make it do that in such a way that
+// This quiz isn't testing our function -- make it do that in such a way that
 // the test passes. Then write a second test that tests that we get the result
 // we expect to get when we call `times_two` with a negative number.
 // No hints, you can do this :)
--- a/exercises/quiz4.rs
+++ b/exercises/quiz4.rs
@@ -0,0 +1,23 @@
+// quiz4.rs
+// This quiz covers the sections:
+// - Modules
+// - Macros
+
+// Write a macro that passes the quiz! No hints this time, you can do it!
+
+// I AM NOT DONE
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_my_macro_world() {
+        assert_eq!(my_macro!("world!"), "Hello world!");
+    }
+
+    #[test]
+    fn test_my_macro_goodbye() {
+        assert_eq!(my_macro!("goodbye!"), "Hello goodbye!");
+    }
+}
--- a/exercises/standard_library_types/README.md
+++ b/exercises/standard_library_types/README.md
@@ -1,5 +1,5 @@
+For the Box exercise check out the chapter [Using Box to Point to Data on the Heap](https://doc.rust-lang.org/book/ch15-01-box.html).
+
 For the Arc exercise check out the chapter [Shared-State Concurrency](https://doc.rust-lang.org/book/ch16-03-shared-state.html) of the Rust Book.

 For the Iterator exercise check out the chapters [Iterator](https://doc.rust-lang.org/book/ch13-02-iterators.html) of the Rust Book and the [Iterator documentation](https://doc.rust-lang.org/stable/std/iter/).
-Do not adjust your monitors-- iterators 1 and 2 are indeed missing. Iterator 3 is a bit challenging so we're leaving space for some exercises to lead up to it!
-
--- a/exercises/standard_library_types/arc1.rs
+++ b/exercises/standard_library_types/arc1.rs
@@ -1,11 +1,12 @@
 // arc1.rs
 // Make this code compile by filling in a value for `shared_numbers` where the
-// TODO comment is and creating an initial binding for `child_numbers`
+// TODO comment is and create an initial binding for `child_numbers`
 // somewhere. Try not to create any copies of the `numbers` Vec!
-// Execute `rustlings help arc1` for hints :)
+// Execute `rustlings hint arc1` for hints :)

 // I AM NOT DONE

+#![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;

@@ -20,7 +21,7 @@ fn main() {
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
-                i += 5;
+                i += 8;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
--- a/exercises/standard_library_types/box1.rs
+++ b/exercises/standard_library_types/box1.rs
@@ -0,0 +1,56 @@
+// box1.rs
+//
+// At compile time, Rust needs to know how much space a type takes up. This becomes problematic
+// for recursive types, where a value can have as part of itself another value of the same type.
+// To get around the issue, we can use a `Box` - a smart pointer used to store data on the heap,
+// which also allows us to wrap a recursive type.
+//
+// The recursive type we're implementing in this exercise is the `cons list` - a data structure
+// frequently found in functional programming languages. Each item in a cons list contains two
+// elements: the value of the current item and the next item. The last item is a value called `Nil`.
+//
+// Step 1: use a `Box` in the enum definition to make the code compile
+// Step 2: create both empty and non-empty cons lists by replacing `unimplemented!()`
+//
+// Note: the tests should not be changed
+//
+// Execute `rustlings hint box1` for hints :)
+
+// I AM NOT DONE
+
+#[derive(PartialEq, Debug)]
+pub enum List {
+    Cons(i32, List),
+    Nil,
+}
+
+fn main() {
+    println!("This is an empty cons list: {:?}", create_empty_list());
+    println!(
+        "This is a non-empty cons list: {:?}",
+        create_non_empty_list()
+    );
+}
+
+pub fn create_empty_list() -> List {
+    unimplemented!()
+}
+
+pub fn create_non_empty_list() -> List {
+    unimplemented!()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_create_empty_list() {
+        assert_eq!(List::Nil, create_empty_list())
+    }
+
+    #[test]
+    fn test_create_non_empty_list() {
+        assert_ne!(create_empty_list(), create_non_empty_list())
+    }
+}
--- a/exercises/standard_library_types/iterators1.rs
+++ b/exercises/standard_library_types/iterators1.rs
@@ -0,0 +1,24 @@
+// iterators1.rs
+// 
+//  Make me compile by filling in the `???`s
+//
+// When performing operations on elements within a collection, iterators are essential.
+// This module helps you get familiar with the structure of using an iterator and 
+// how to go through elements within an iterable collection.
+// 
+// Execute `rustlings hint iterators1` for hints :D
+
+// I AM NOT DONE
+
+fn main () {
+    let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
+
+    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2.1
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+}
--- a/exercises/standard_library_types/iterators2.rs
+++ b/exercises/standard_library_types/iterators2.rs
@@ -1,8 +1,10 @@
 // iterators2.rs
-// In this module, you'll learn some of unique advantages that iterators can offer
-// Step 1. Complete the `capitalize_first` function to pass the first two cases
-// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it returns a vector of strings as well
-// Step 3. Apply the `capitalize_first` function again to a list, but try and ensure it returns a single string
+// In this module, you'll learn some of the unique advantages that iterators can offer.
+// Step 1. Complete the `capitalize_first` function to pass the first two cases.
+// Step 2. Apply the `capitalize_first` function to a vector of strings.
+//         Ensure that it returns a vector of strings as well.
+// Step 3. Apply the `capitalize_first` function again to a list.
+//         Try to ensure it returns a single string.
 // As always, there are hints if you execute `rustlings hint iterators2`!

 // I AM NOT DONE
--- a/exercises/standard_library_types/iterators4.rs
+++ b/exercises/standard_library_types/iterators4.rs
@@ -3,13 +3,13 @@
 // I AM NOT DONE

 pub fn factorial(num: u64) -> u64 {
-    // Complete this function to return factorial of num
+    // Complete this function to return the factorial of num
    // Do not use:
    // - return
-    // For extra fun don't use:
+    // Try not to use:
    // - imperative style loops (for, while)
    // - additional variables
-    // For the most fun don't use:
+    // For an extra challenge, don't use:
    // - recursion
    // Execute `rustlings hint iterators4` for hints.
 }
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -1,6 +1,5 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
-// No hints, just do it!

 // I AM NOT DONE

--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -0,0 +1,71 @@
+// structs3.rs
+// Structs contain more than simply some data, they can also have logic, in this
+// exercise we have defined the Package struct and we want to test some logic attached to it,
+// make the code compile and the tests pass! If you have issues execute `rustlings hint structs3`
+
+// I AM NOT DONE
+
+#[derive(Debug)]
+struct Package {
+    sender_country: String,
+    recipient_country: String,
+    weight_in_grams: i32,
+}
+
+impl Package {
+    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
+        if weight_in_grams <= 0 {
+            // Something goes here...
+        } else {
+            return Package {
+                sender_country,
+                recipient_country,
+                weight_in_grams,
+            };
+        }
+    }
+
+    fn is_international(&self) -> ??? {
+        // Something goes here...
+    }
+
+    fn get_fees(&self, cents_per_gram: i32) -> ??? {
+        // Something goes here... 
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[should_panic]
+    fn fail_creating_weightless_package() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Austria");
+
+        Package::new(sender_country, recipient_country, -2210);
+    }
+
+    #[test]
+    fn create_international_package() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Russia");
+
+        let package = Package::new(sender_country, recipient_country, 1200);
+
+        assert!(package.is_international());
+    }
+
+    #[test]
+    fn calculate_transport_fees() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Spain");
+
+        let cents_per_gram = ???;
+
+        let package = Package::new(sender_country, recipient_country, 1500);
+
+        assert_eq!(package.get_fees(cents_per_gram), 4500);
+    }
+}
--- a/exercises/test2.rs
+++ b/exercises/test2.rs
@@ -1,30 +0,0 @@
-// test2.rs
-// This is a test for the following sections:
-// - Strings
-
-// Ok, here are a bunch of values-- some are `Strings`, some are `&strs`. Your
-// task is to call one of these two functions on each value depending on what
-// you think each value is. That is, add either `string_slice` or `string`
-// before the parentheses on each line. If you're right, it will compile!
-
-// I AM NOT DONE
-
-fn string_slice(arg: &str) {
-    println!("{}", arg);
-}
-fn string(arg: String) {
-    println!("{}", arg);
-}
-
-fn main() {
-    ("blue");
-    ("red".to_string());
-    (String::from("hi"));
-    ("rust is fun!".to_owned());
-    ("nice weather".into());
-    (format!("Interpolation {}", "Station"));
-    (&String::from("abc")[0..1]);
-    ("  hello there ".trim());
-    ("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ("mY sHiFt KeY iS sTiCkY".to_lowercase());
-}
--- a/exercises/test4.rs
+++ b/exercises/test4.rs
@@ -1,14 +0,0 @@
-// test4.rs
-// This test covers the sections:
-// - Modules
-// - Macros
-
-// Write a macro that passes the test! No hints this time, you can do it!
-
-// I AM NOT DONE
-
-fn main() {
-    if my_macro!("world!") != "Hello world!" {
-        panic!("Oh no! Wrong output!");
-    }
-}
--- a/exercises/tests/tests1.rs
+++ b/exercises/tests/tests1.rs
@@ -1,7 +1,7 @@
 // tests1.rs
 // Tests are important to ensure that your code does what you think it should do.
 // Tests can be run on this file with the following command:
-// rustlings run --test exercises/tests/tests1.rs
+// rustlings run tests1

 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Execute `rustlings hint tests1` for hints :)
--- a/exercises/tests/tests3.rs
+++ b/exercises/tests/tests3.rs
@@ -18,4 +18,9 @@ mod tests {
    fn is_true_when_even() {
        assert!();
    }
+
+    #[test]
+    fn is_false_when_odd() {
+        assert!();
+    }
 }
--- a/exercises/threads/threads1.rs
+++ b/exercises/threads/threads1.rs
@@ -1,6 +1,6 @@
 // threads1.rs
 // Make this compile! Execute `rustlings hint threads1` for hints :)
-// The idea is the thread spawned on line 19 is completing jobs while the main thread is
+// The idea is the thread spawned on line 21 is completing jobs while the main thread is
 // monitoring progress until 10 jobs are completed. If you see 6 lines
 // of "waiting..." and the program ends without timing out when running,
 // you've got it :)
--- a/exercises/traits/README.md
+++ b/exercises/traits/README.md
@@ -0,0 +1,20 @@
+### Traits
+
+A trait is a collection of methods.
+
+Data types can implement traits. To do so, the methods making up the trait are defined for the data type. For example, the `String` data type implements the `From<&str>` trait. This allows a user to write `String::from("hello")`.
+
+In this way, traits are somewhat similar to Java interfaces and C++ abstract classes.
+
+Some additional common Rust traits include:
+
+ `Clone` (the `clone` method),
+ `Display` (which allows formatted display via `{}`), and
+ `Debug` (which allows formatted display via `{:?}`).
+
+Because traits indicate shared behavior between data types, they are useful when writing generics.
+
+
+#### Book Sections
+
+- [Traits](https://doc.rust-lang.org/book/ch10-02-traits.html)
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -0,0 +1,43 @@
+// traits1.rs
+// Time to implement some traits!
+//
+// Your task is to implement the trait
+// `AppendBar' for the type `String'.
+//
+// The trait AppendBar has only one function,
+// which appends "Bar" to any object
+// implementing this trait.
+
+// I AM NOT DONE
+
+trait AppendBar {
+    fn append_bar(self) -> Self;
+}
+
+impl AppendBar for String {
+    //Add your code here
+}
+
+fn main() {
+    let s = String::from("Foo");
+    let s = s.append_bar();
+    println!("s: {}", s);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn is_FooBar() {
+        assert_eq!(String::from("Foo").append_bar(), String::from("FooBar"));
+    }
+
+    #[test]
+    fn is_BarBar() {
+        assert_eq!(
+            String::from("").append_bar().append_bar(),
+            String::from("BarBar")
+        );
+    }
+}
--- a/exercises/traits/traits2.rs
+++ b/exercises/traits/traits2.rs
@@ -0,0 +1,31 @@
+// traits2.rs
+//
+// Your task is to implement the trait
+// `AppendBar' for a vector of strings.
+//
+// To implement this trait, consider for
+// a moment what it means to 'append "Bar"'
+// to a vector of strings.
+//
+// No boiler plate code this time,
+// you can do this!
+
+// I AM NOT DONE
+
+trait AppendBar {
+    fn append_bar(self) -> Self;
+}
+
+//TODO: Add your code here
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn is_vec_pop_eq_bar() {
+        let mut foo = vec![String::from("Foo")].append_bar();
+        assert_eq!(foo.pop().unwrap(), String::from("Bar"));
+        assert_eq!(foo.pop().unwrap(), String::from("Foo"));
+    }
+}
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -4,7 +4,7 @@
 // About this `I AM NOT DONE` thing:
 // 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, you the `I AM NOT DONE` comment below.
+// feel ready for the next exercise, remove the `I AM NOT DONE` comment below.

 // I AM NOT DONE

--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -6,6 +6,6 @@
 fn main() {
    let x = 3;
    println!("Number {}", x);
-    x = 5;
+    x = 5; // don't change this line
    println!("Number {}", x);
 }
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -0,0 +1,11 @@
+// variables5.rs
+// Make me compile! Execute the command `rustlings hint variables5` if you want a hint :)
+
+// I AM NOT DONE
+
+fn main() {
+    let number = "T-H-R-E-E";
+    println!("Spell a Number : {}", number);
+    number = 3;
+    println!("Number plus two is : {}", number + 2);
+}
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -0,0 +1,9 @@
+// variables6.rs
+// Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
+
+// I AM NOT DONE
+
+const NUMBER = 3;
+fn main() {
+    println!("Number {}", NUMBER);
+}
--- a/info.toml
+++ b/info.toml
@@ -5,7 +5,7 @@ name = "variables1"
 path = "exercises/variables/variables1.rs"
 mode = "compile"
 hint = """
-Hint: The declaration on line 5 is missing a keyword that is needed in Rust
+Hint: The declaration on line 12 is missing a keyword that is needed in Rust
 to create a new variable binding."""

 [[exercises]]
@@ -15,7 +15,7 @@ mode = "compile"
 hint = """
 The compiler message is saying that Rust cannot infer the type that the
 variable binding `x` has with what is given here.
-What happens if you annotate line 5 with a type annotation?
+What happens if you annotate line 7 with a type annotation?
 What if you give x a value?
 What if you do both?
 What type should x be, anyway?
@@ -36,11 +36,41 @@ path = "exercises/variables/variables4.rs"
 mode = "compile"
 hint = """
 Oops! In this exercise, we have a variable binding that we've created on
-line 5, and we're trying to use it on line 6, but we haven't given it a
+line 7, and we're trying to use it on line 8, but we haven't given it a
 value. We can't print out something that isn't there; try giving x a value!
 This is an error that can cause bugs that's very easy to make in any
 programming language -- thankfully the Rust compiler has caught this for us!"""

+[[exercises]]
+name = "variables5"
+path = "exercises/variables/variables5.rs"
+mode = "compile"
+hint = """
+In variables3 we already learned how to make an immutable variable mutable
+using a special keyword. Unfortunately this doesn't help us much in this exercise
+because we want to assign a different typed value to an existing variable. Sometimes
+you may also like to reuse existing variable names because you are just converting
+values to different types like in this exercise.
+Fortunately Rust has a powerful solution to this problem: 'Shadowing'!
+You can read more about 'Shadowing' in the book's section 'Variables and Mutability':
+https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
+Try to solve this exercise afterwards using this technique."""
+
+[[exercises]]
+name = "variables6"
+path = "exercises/variables/variables6.rs"
+mode = "compile"
+hint = """
+We know about variables and mutability, but there is another important type of
+variable available; constants.
+Constants are always immutable and they are declared with keyword 'const' rather
+than keyword 'let'.
+Constants types must also always be annotated.
+
+Read more about constants under 'Differences Between Variables and Constants' in the book's section 'Variables and Mutability':
+https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#differences-between-variables-and-constants
+"""
+
 # IF

 [[exercises]]
@@ -57,6 +87,15 @@ Remember in Rust that:
 - `if`/`else` conditionals are expressions
 - Each condition is followed by a `{}` block."""

+[[exercises]]
+name = "if2"
+path = "exercises/if/if2.rs"
+mode = "test"
+hint = """
+For that first compiler error, it's important in Rust that each conditional
+block return the same type! To get the tests passing, you will need a couple
+conditions checking different input values."""
+
 # FUNCTIONS

 [[exercises]]
@@ -90,7 +129,7 @@ name = "functions4"
 path = "exercises/functions/functions4.rs"
 mode = "compile"
 hint = """
-The error message points to line 12 and says it expects a type after the
+The error message points to line 14 and says it expects a type after the
 `->`. This is where the function's return type should be-- take a look at
 the `is_even` function for an example!"""

@@ -110,8 +149,8 @@ They are not the same. There are two solutions:
 # TEST 1

 [[exercises]]
-name = "test1"
-path = "exercises/test1.rs"
+name = "quiz1"
+path = "exercises/quiz1.rs"
 mode = "test"
 hint = "No hints this time ;)"

@@ -152,8 +191,8 @@ https://doc.rust-lang.org/book/ch04-03-slices.html
 and use the starting and ending indices of the items in the Array
 that you want to end up in the slice.

-If you're curious why the right hand of the `==` comparison does not
-have an ampersand for a reference since the left hand side is a
+If you're curious why the first argument of `assert_eq!` does not
+have an ampersand for a reference since the second argument is a
 reference, take a look at the Deref coercions section of the book:
 https://doc.rust-lang.org/book/ch15-02-deref.html"""

@@ -171,7 +210,7 @@ of the tuple. You can do it!!"""
 [[exercises]]
 name = "primitive_types6"
 path = "exercises/primitive_types/primitive_types6.rs"
-mode = "compile"
+mode = "test"
 hint = """
 While you could use a destructuring `let` for the tuple here, try
 indexing into it instead, as explained in the last example of the
@@ -185,13 +224,35 @@ Now you have another tool in your toolbox!"""
 name = "structs1"
 path = "exercises/structs/structs1.rs"
 mode = "test"
-hint = "No hints this time ;)"
+hint = """
+Rust has more than one type of struct. Both variants are used to package related data together.
+On the one hand, there are normal, or classic, structs. These are named collections of related data stored in fields.
+The other variant is tuple structs. Basically just named tuples.
+In this exercise you need to implement one of each kind.
+
+Read more about structs in The Book: https://doc.rust-lang.org/stable/book/ch05-00-structs.html"""

 [[exercises]]
 name = "structs2"
 path = "exercises/structs/structs2.rs"
 mode = "test"
-hint = "No hints this time ;)"
+hint = """
+Creating instances of structs is easy, all you need to do is assign some values to its fields.
+There is however some shortcuts that can be taken when instantiating structs.
+Have a look in The Book, to find out more: https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax"""
+
+[[exercises]]
+name = "structs3"
+path = "exercises/structs/structs3.rs"
+mode = "test"
+hint = """
+The new method needs to panic if the weight is physically impossible :), how do we do that in Rust?
+
+For is_international: What makes a package international? Seems related to the places it goes through right?
+
+For calculate_transport_fees: Bigger is more expensive usually, we don't have size, but something may fit the bill here :)
+
+Have a look in The Book, to find out more about method implementations: https://doc.rust-lang.org/book/ch05-03-method-syntax.html"""

 # STRINGS

@@ -214,13 +275,13 @@ mode = "compile"
 hint = """
 Yes, it would be really easy to fix this by just changing the value bound to `word` to be a
 string slice instead of a `String`, wouldn't it?? There is a way to add one character to line
-6, though, that will coerce the `String` into a string slice."""
+9, though, that will coerce the `String` into a string slice."""

 # TEST 2

 [[exercises]]
-name = "test2"
-path = "exercises/test2.rs"
+name = "quiz2"
+path = "exercises/quiz2.rs"
 mode = "compile"
 hint = "No hints this time ;)"

@@ -282,8 +343,8 @@ can negate the result of what you're doing using `!`, like `assert!(!having_fun(
 # TEST 3

 [[exercises]]
-name = "test3"
-path = "exercises/test3.rs"
+name = "quiz3"
+path = "exercises/quiz3.rs"
 mode = "test"
 hint = "No hints this time ;)"

@@ -309,6 +370,58 @@ its internal structure (the `fruits` and `veggies` modules and
 associated constants). It's almost there except for one keyword missing for
 each constant."""

+# COLLECTIONS
+
+[[exercises]]
+name = "collections1"
+path = "exercises/collections/vec1.rs"
+mode = "test"
+hint = """
+In Rust, there are two ways to define a Vector.
+
+1. One way is to use the `Vec::new()` function to create a new vector
+  and fill it with the `push()` method.
+
+2. The second way, which is simpler is to use the `vec![]` macro and
+  define your elements inside the square brackets.
+
+Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
+of the Rust book to learn more.
+"""
+
+[[exercises]]
+name = "collections2"
+path = "exercises/collections/vec2.rs"
+mode = "test"
+hint = """
+Hint 1: `i` is each element from the Vec as they are being iterated.
+  Can you try multiplying this?
+
+Hint 2: Check the suggestion from the compiler error ;)
+"""
+
+[[exercises]]
+name = "collections3"
+path = "exercises/collections/hashmap1.rs"
+mode = "test"
+hint = """
+Hint 1: Take a look at the return type of the function to figure out
+  the type for the `basket`.
+
+Hint 2: Number of fruits should be at least 5. And you have to put
+  at least three different types of fruits.
+"""
+
+[[exercises]]
+name = "collections4"
+path = "exercises/collections/hashmap2.rs"
+mode = "test"
+hint = """
+Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
+
+Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
+"""
+
 # MACROS

 [[exercises]]
@@ -353,9 +466,9 @@ The way macros are written, it wants to see something between each
 # TEST 4

 [[exercises]]
-name = "test4"
-path = "exercises/test4.rs"
-mode = "compile"
+name = "quiz4"
+path = "exercises/quiz4.rs"
+mode = "test"
 hint = "No hints this time ;)"

 # MOVE SEMANTICS
@@ -365,8 +478,8 @@ name = "move_semantics1"
 path = "exercises/move_semantics/move_semantics1.rs"
 mode = "compile"
 hint = """
-So you've got the "cannot borrow immutable local variable `vec1` as mutable" error on line 11,
-right? The fix for this is going to be adding one keyword, and the addition is NOT on line 11
+So you've got the "cannot borrow immutable local variable `vec1` as mutable" error on line 13,
+right? The fix for this is going to be adding one keyword, and the addition is NOT on line 13
 where the error is."""

 [[exercises]]
@@ -375,8 +488,8 @@ path = "exercises/move_semantics/move_semantics2.rs"
 mode = "compile"
 hint = """
 So `vec0` is being *moved* into the function `fill_vec` when we call it on
-line 7, which means it gets dropped at the end of `fill_vec`, which means we
-can't use `vec0` again on line 10 (or anywhere else in `main` after the
+line 10, which means it gets dropped at the end of `fill_vec`, which means we
+can't use `vec0` again on line 13 (or anywhere else in `main` after the
 `fill_vec` call for that matter). We could fix this in a few ways, try them
 all!
 1. Make another, separate version of the data that's in `vec0` and pass that
@@ -462,7 +575,7 @@ mode = "test"
 hint = """
 First hint: To figure out what type should go where the ??? is, take a look
 at the test helper function `test_with_str`, since it returns whatever
-`read_and_validate` returns and`test_with_str` has its signature fully
+`read_and_validate` returns and `test_with_str` has its signature fully
 specified.


@@ -497,14 +610,34 @@ https://doc.rust-lang.org/std/result/#results-must-be-used"""

 [[exercises]]
 name = "option1"
-path = "exercises/error_handling/option1.rs"
-mode = "test"
+path = "exercises/option/option1.rs"
+mode = "compile"
 hint = """
-Try using a `match` statement where the arms are `Some(thing)` and `None`.
-Or set a default value to print out if you get `None` by using the
-function `unwrap_or`.
-Or use an `if let` statement on the result of `pop()` to both destructure
-a `Some` value and only print out something if we have a value!"""
+Hint 1: Check out some functions of Option:
+is_some
+is_none
+unwrap
+
+and:
+pattern matching
+
+Hint 2: There are no sensible defaults for the value of an Array; the values need to be filled before use.
+"""
+
+[[exercises]]
+name = "option2"
+path = "exercises/option/option2.rs"
+mode = "compile"
+hint = """
+check out:
+https://doc.rust-lang.org/rust-by-example/flow_control/if_let.html
+https://doc.rust-lang.org/rust-by-example/flow_control/while_let.html
+
+Remember that Options can be stacked in if let and while let.
+For example: Some(Some(variable)) = variable2
+
+
+"""

 [[exercises]]
 name = "result1"
@@ -515,8 +648,42 @@ hint = """
 It should be doing some checking, returning an `Err` result if those checks fail, and only
 returning an `Ok` result if those checks determine that everything is... okay :)"""

+#  CLIPPY
+
+[[exercises]]
+name = "clippy1"
+path = "exercises/clippy/clippy1.rs"
+mode = "clippy"
+hint = """
+Floating point calculations are usually imprecise, so asking if two values are exactly equal is asking for trouble"""
+
+[[exercises]]
+name = "clippy2"
+path = "exercises/clippy/clippy2.rs"
+mode = "clippy"
+hint = """
+`for` loops over Option values are more clearly expressed as an `if let`"""
+
 # STANDARD LIBRARY TYPES

+[[exercises]]
+name = "box1"
+path = "exercises/standard_library_types/box1.rs"
+mode = "test"
+hint = """
+Step 1
+The compiler's message should help: since we cannot store the value of the actual type
+when working with recursive types, we need to store a reference (pointer) to its value.
+We should, therefore, place our `List` inside a `Box`. More details in the book here:
+https://doc.rust-lang.org/book/ch15-01-box.html#enabling-recursive-types-with-boxes
+
+Step 2
+Creating an empty list should be fairly straightforward (hint: peek at the assertions).
+For a non-empty list keep in mind that we want to use our Cons "list builder".
+Although the current list is one of integers (i32), feel free to change the definition
+and try other types!
+"""
+
 [[exercises]]
 name = "arc1"
 path = "exercises/standard_library_types/arc1.rs"
@@ -529,6 +696,27 @@ inside the loop but still in the main thread.
 `child_numbers` should be a clone of the Arc of the numbers instead of a
 thread-local copy of the numbers."""

+[[exercises]]
+name = "iterators1"
+path = "exercises/standard_library_types/iterators1.rs"
+mode = "compile"
+hint = """
+Step 1:
+We need to apply something to the collection `my_fav_fruits` before we start to go through
+it. What could that be? Take a look at the struct definition for a vector for inspiration:
+https://doc.rust-lang.org/std/vec/struct.Vec.html.
+
+
+Step 2 & step 2.1:
+Very similar to the lines above and below. You've got this!
+
+
+Step 3:
+An iterator goes through all elements in a collection, but what if we've run out of
+elements? What should we expect here? If you're stuck, take a look at 
+https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
+"""
+
 [[exercises]]
 name = "iterators2"
 path = "exercises/standard_library_types/iterators2.rs"
@@ -567,10 +755,66 @@ name = "iterators4"
 path = "exercises/standard_library_types/iterators4.rs"
 mode = "test"
 hint = """
-In an imperative language you might write a for loop to iterate through
-multiply the values into a mutable variable. Or you might write code more
-functionally with recursion and a match clause. But you can also use ranges
-and iterators to solve this in rust."""
+In an imperative language, you might write a for loop that updates
+a mutable variable. Or, you might write code utilizing recursion
+and a match clause. In Rust you can take another functional
+approach, computing the factorial elegantly with ranges and iterators."""
+
+# TRAITS
+
+[[exercises]]
+name = "traits1"
+path = "exercises/traits/traits1.rs"
+mode = "test"
+hint = """
+A discussion about Traits in Rust can be found at:
+https://doc.rust-lang.org/book/ch10-02-traits.html
+"""
+
+[[exercises]]
+name = "traits2"
+path = "exercises/traits/traits2.rs"
+mode = "test"
+hint = """
+Notice how the trait takes ownership of 'self',and returns `Self'.
+Try mutating the incoming string vector.
+
+Vectors provide suitable methods for adding an element at the end. See
+the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""
+
+# Generics
+
+[[exercises]]
+name = "generics1"
+path = "exercises/generics/generics1.rs"
+mode = "compile"
+hint = """
+Vectors in rust make use of generics to create dynamically sized arrays of any type.
+You need to tell the compiler what type we are pushing onto this vector."""
+
+[[exercises]]
+name = "generics2"
+path = "exercises/generics/generics2.rs"
+mode = "test"
+hint = """
+Currently we are wrapping only values of type 'u32'.
+Maybe we could update the explicit references to this data type somehow?
+
+If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
+"""
+
+[[exercises]]
+name = "generics3"
+path = "exercises/generics/generics3.rs"
+mode = "test"
+hint = """
+To find the best solution to this challenge you're going to need to think back to your
+knowledge of traits, specifically Trait Bound Syntax -  you may also need this: "use std::fmt::Display;"
+
+This is definitely harder than the last two exercises! You need to think about not only making the
+ReportCard struct generic, but also the correct property - you will need to change the implementation
+of the struct slightly too...you can do it!
+"""

 # THREADS

@@ -610,3 +854,44 @@ answers and don't understand why they work and yours doesn't.
 If you've learned from the sample solutions, I encourage you to come
 back to this exercise and try it again in a few days to reinforce
 what you've learned :)"""
+
+# TYPE CONVERSIONS
+
+[[exercises]]
+name = "using_as"
+path = "exercises/conversions/using_as.rs"
+mode = "test"
+hint = """
+Use the `as` operator to cast one of the operands in the last line of the
+`average` function into the expected return type."""
+
+[[exercises]]
+name = "from_into"
+path = "exercises/conversions/from_into.rs"
+mode = "test"
+hint = """
+Follow the steps provided right before the `From` implementation"""
+
+[[exercises]]
+name = "try_from_into"
+path = "exercises/conversions/try_from_into.rs"
+mode = "test"
+hint = """
+Follow the steps provided right before the `TryFrom` implementation.
+You can also use the example at https://doc.rust-lang.org/std/convert/trait.TryFrom.html"""
+
+[[exercises]]
+name = "as_ref_mut"
+path = "exercises/conversions/as_ref_mut.rs"
+mode = "test"
+hint = """
+Add AsRef<str> as a trait bound to the functions."""
+
+[[exercises]]
+name = "from_str"
+path = "exercises/conversions/from_str.rs"
+mode = "test"
+hint = """
+The implementation of FromStr should return an Ok with a Person object,
+or an Err with a string if the string is not valid.
+This is almost like the `try_from_into` exercise."""
--- a/install.ps1
+++ b/install.ps1
@@ -35,7 +35,7 @@ if (Get-Command cargo -ErrorAction SilentlyContinue) {
 function vercomp($v1, $v2) {
    if ($v1 -eq $v2) {
       return 0
-    } 
+    }

    $v1 = $v1.Replace(".", "0")
    $v2 = $v2.Replace(".", "0")
@@ -53,7 +53,7 @@ function vercomp($v1, $v2) {
 }

 $rustVersion = $(rustc --version).Split(" ")[1]
-$minRustVersion = "1.31"
+$minRustVersion = "1.39"
 if ((vercomp $rustVersion $minRustVersion) -eq 2) {
    Write-Host "WARNING: Rust version is too old: $rustVersion - needs at least $minRustVersion"
    Write-Host "Please update Rust with 'rustup update'"
@@ -72,6 +72,7 @@ if (!($LASTEXITCODE -eq 0)) {
 # but anyone running pwsh 5 will have to pass the argument.
 $version = Invoke-WebRequest -UseBasicParsing https://api.github.com/repos/rust-lang/rustlings/releases/latest `
    | ConvertFrom-Json | Select-Object -ExpandProperty tag_name
+
 Write-Host "Checking out version $version..."
 Set-Location $path
 git checkout -q tags/$version
@@ -82,4 +83,12 @@ if (!(Get-Command rustlings -ErrorAction SilentlyContinue)) {
    Write-Host "WARNING: Please check that you have '~/.cargo/bin' in your PATH environment variable!"
 }

+# Checking whether Clippy is installed.
+# Due to a bug in Cargo, this must be done with Rustup: https://github.com/rust-lang/rustup/issues/1514
+$clippy = (rustup component list | Select-String "clippy" | Select-String "installed") | Out-String
+if (!$clippy) {
+    Write-Host "Installing the 'cargo-clippy' executable..."
+    rustup component add clippy
+}
+
 Write-Host "All done! Run 'rustlings' to get started."
--- a/install.sh
+++ b/install.sh
@@ -7,7 +7,7 @@ if [ -x "$(command -v git)" ]
 then
    echo "SUCCESS: Git is installed"
 else
-    echo "WARNING: Git does not seem to be installed."
+    echo "ERROR: Git does not seem to be installed."
    echo "Please download Git using your package manager or over https://git-scm.com/!"
    exit 1
 fi
@@ -16,7 +16,7 @@ if [ -x "$(command -v rustc)" ]
 then
    echo "SUCCESS: Rust is installed"
 else
-    echo "WARNING: Rust does not seem to be installed."
+    echo "ERROR: Rust does not seem to be installed."
    echo "Please download Rust using https://rustup.rs!"
    exit 1
 fi
@@ -25,11 +25,27 @@ if [ -x "$(command -v cargo)" ]
 then
    echo "SUCCESS: Cargo is installed"
 else
-    echo "WARNING: Cargo does not seem to be installed."
+    echo "ERROR: Cargo does not seem to be installed."
    echo "Please download Rust and Cargo using https://rustup.rs!"
    exit 1
 fi

+# Look up python installations, starting with 3 with a fallback of 2
+if [ -x "$(command -v python3)" ]
+then
+    PY="$(command -v python3)"
+elif [ -x "$(command -v python)" ]
+then
+    PY="$(command -v python)"
+elif [ -x "$(command -v python2)" ]
+then
+    PY="$(command -v python2)"
+else
+    echo "ERROR: No working python installation was found"
+    echo "Please install python and add it to the PATH variable"
+    exit 1
+fi
+
 # Function that compares two versions strings v1 and v2 given in arguments (e.g 1.31 and 1.33.0).
 # Returns 1 if v1 > v2, 0 if v1 == v2, 2 if v1 < v2.
 function vercomp() {
@@ -71,11 +87,11 @@ function vercomp() {
 }

 RustVersion=$(rustc --version | cut -d " " -f 2)
-MinRustVersion=1.31
+MinRustVersion=1.39
 vercomp $RustVersion $MinRustVersion
 if [ $? -eq 2 ]
 then
-    echo "WARNING: Rust version is too old: $RustVersion - needs at least $MinRustVersion"
+    echo "ERROR: Rust version is too old: $RustVersion - needs at least $MinRustVersion"
    echo "Please update Rust with 'rustup update'"
    exit 1
 else
@@ -86,17 +102,46 @@ Path=${1:-rustlings/}
 echo "Cloning Rustlings at $Path..."
 git clone -q https://github.com/rust-lang/rustlings $Path

-Version=$(curl -s https://api.github.com/repos/rust-lang/rustlings/releases/latest | python -c "import json,sys;obj=json.load(sys.stdin);print(obj['tag_name']);")
-echo "Checking out version $Version..."
 cd $Path
-git checkout -q tags/$Version
+
+Version=$(curl -s https://api.github.com/repos/rust-lang/rustlings/releases/latest | ${PY} -c "import json,sys;obj=json.load(sys.stdin);print(obj['tag_name']);")
+CargoBin="${CARGO_HOME:-$HOME/.cargo}/bin"
+
+if [[ -z ${Version} ]]
+then
+    echo "The latest tag version could not be fetched remotely."
+    echo "Using the local git repository..."
+    Version=$(ls -tr .git/refs/tags/ | tail -1)
+    if [[ -z ${Version}  ]]
+    then
+        echo "No valid tag version found"
+        echo "Rustlings will be installed using the main branch"
+        Version="main"
+    else
+        Version="tags/${Version}"
+    fi
+else
+    Version="tags/${Version}"
+fi
+
+echo "Checking out version $Version..."
+git checkout -q ${Version}

 echo "Installing the 'rustlings' executable..."
 cargo install --force --path .

 if ! [ -x "$(command -v rustlings)" ]
 then
-    echo "WARNING: Please check that you have '~/.cargo/bin' in your PATH environment variable!"
+    echo "WARNING: Please check that you have '$CargoBin' in your PATH environment variable!"
+fi
+
+# Checking whether Clippy is installed.
+# Due to a bug in Cargo, this must be done with Rustup: https://github.com/rust-lang/rustup/issues/1514
+Clippy=$(rustup component list | grep "clippy" | grep "installed")
+if [ -z "$Clippy" ]
+then
+    echo "Installing the 'cargo-clippy' executable..."
+    rustup component add clippy
 fi

 echo "All done! Run 'rustlings' to get started."
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -1,24 +1,37 @@
 use regex::Regex;
 use serde::Deserialize;
 use std::fmt::{self, Display, Formatter};
-use std::fs::{remove_file, File};
+use std::fs::{self, remove_file, File};
 use std::io::Read;
 use std::path::PathBuf;
-use std::process::{self, Command, Output};
+use std::process::{self, Command};

 const RUSTC_COLOR_ARGS: &[&str] = &["--color", "always"];
 const I_AM_DONE_REGEX: &str = r"(?m)^\s*///?\s*I\s+AM\s+NOT\s+DONE";
 const CONTEXT: usize = 2;
+const CLIPPY_CARGO_TOML_PATH: &str = "./exercises/clippy/Cargo.toml";

+// Get a temporary file name that is hopefully unique
+#[inline]
 fn temp_file() -> String {
-    format!("./temp_{}", process::id())
+    let thread_id: String = format!("{:?}", std::thread::current().id())
+        .chars()
+        .filter(|c| c.is_alphanumeric())
+        .collect();
+
+    format!("./temp_{}_{}", process::id(), thread_id)
 }

+// The mode of the exercise.
 #[derive(Deserialize, Copy, Clone)]
 #[serde(rename_all = "lowercase")]
 pub enum Mode {
+    // Indicates that the exercise should be compiled as a binary
    Compile,
+    // Indicates that the exercise should be compiled as a test harness
    Test,
+    // Indicates that the exercise should be linted with clippy
+    Clippy,
 }

 #[derive(Deserialize)]
@@ -26,30 +39,74 @@ pub struct ExerciseList {
    pub exercises: Vec<Exercise>,
 }

+// A representation of a rustlings exercise.
+// This is deserialized from the accompanying info.toml file
 #[derive(Deserialize)]
 pub struct Exercise {
+    // Name of the exercise
    pub name: String,
+    // The path to the file containing the exercise's source code
    pub path: PathBuf,
+    // The mode of the exercise (Test, Compile, or Clippy)
    pub mode: Mode,
+    // The hint text associated with the exercise
    pub hint: String,
 }

+// An enum to track of the state of an Exercise.
+// An Exercise can be either Done or Pending
 #[derive(PartialEq, Debug)]
 pub enum State {
+    // The state of the exercise once it's been completed
    Done,
+    // The state of the exercise while it's not completed yet
    Pending(Vec<ContextLine>),
 }

+// The context information of a pending exercise
 #[derive(PartialEq, Debug)]
 pub struct ContextLine {
+    // The source code that is still pending completion
    pub line: String,
+    // The line number of the source code still pending completion
    pub number: usize,
+    // Whether or not this is important
    pub important: bool,
 }

+// The result of compiling an exercise
+pub struct CompiledExercise<'a> {
+    exercise: &'a Exercise,
+    _handle: FileHandle,
+}
+
+impl<'a> CompiledExercise<'a> {
+    // Run the compiled exercise
+    pub fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
+        self.exercise.run()
+    }
+}
+
+// A representation of an already executed binary
+#[derive(Debug)]
+pub struct ExerciseOutput {
+    // The textual contents of the standard output of the binary
+    pub stdout: String,
+    // The textual contents of the standard error of the binary
+    pub stderr: String,
+}
+
+struct FileHandle;
+
+impl Drop for FileHandle {
+    fn drop(&mut self) {
+        clean();
+    }
+}
+
 impl Exercise {
-    pub fn compile(&self) -> Output {
-        match self.mode {
+    pub fn compile(&self) -> Result<CompiledExercise, ExerciseOutput> {
+        let cmd = match self.mode {
            Mode::Compile => Command::new("rustc")
                .args(&[self.path.to_str().unwrap(), "-o", &temp_file()])
                .args(RUSTC_COLOR_ARGS)
@@ -58,18 +115,80 @@ impl Exercise {
                .args(&["--test", self.path.to_str().unwrap(), "-o", &temp_file()])
                .args(RUSTC_COLOR_ARGS)
                .output(),
+            Mode::Clippy => {
+                let cargo_toml = format!(
+                    r#"[package]
+name = "{}"
+version = "0.0.1"
+edition = "2018"
+[[bin]]
+name = "{}"
+path = "{}.rs""#,
+                    self.name, self.name, self.name
+                );
+                fs::write(CLIPPY_CARGO_TOML_PATH, cargo_toml)
+                    .expect("Failed to write 📎 Clippy 📎 Cargo.toml file.");
+                // To support the ability to run the clipy exercises, build
+                // an executable, in addition to running clippy. With a
+                // compilation failure, this would silently fail. But we expect
+                // clippy to reflect the same failure while compiling later.
+                Command::new("rustc")
+                    .args(&[self.path.to_str().unwrap(), "-o", &temp_file()])
+                    .args(RUSTC_COLOR_ARGS)
+                    .output()
+                    .expect("Failed to compile!");
+                // Due to an issue with Clippy, a cargo clean is required to catch all lints.
+                // See https://github.com/rust-lang/rust-clippy/issues/2604
+                // This is already fixed on Clippy's master branch. See this issue to track merging into Cargo:
+                // https://github.com/rust-lang/rust-clippy/issues/3837
+                Command::new("cargo")
+                    .args(&["clean", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
+                    .args(RUSTC_COLOR_ARGS)
+                    .output()
+                    .expect("Failed to run 'cargo clean'");
+                Command::new("cargo")
+                    .args(&["clippy", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
+                    .args(RUSTC_COLOR_ARGS)
+                    .args(&["--", "-D", "warnings"])
+                    .output()
+            }
+        }
+        .expect("Failed to run 'compile' command.");
+
+        if cmd.status.success() {
+            Ok(CompiledExercise {
+                exercise: &self,
+                _handle: FileHandle,
+            })
+        } else {
+            clean();
+            Err(ExerciseOutput {
+                stdout: String::from_utf8_lossy(&cmd.stdout).to_string(),
+                stderr: String::from_utf8_lossy(&cmd.stderr).to_string(),
+            })
        }
-        .expect("Failed to run 'compile' command.")
    }

-    pub fn run(&self) -> Output {
-        Command::new(&temp_file())
+    fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
+        let arg = match self.mode {
+            Mode::Test => "--show-output",
+            _ => "",
+        };
+        let cmd = Command::new(&temp_file())
+            .arg(arg)
            .output()
-            .expect("Failed to run 'run' command")
-    }
+            .expect("Failed to run 'run' command");

-    pub fn clean(&self) {
-        let _ignored = remove_file(&temp_file());
+        let output = ExerciseOutput {
+            stdout: String::from_utf8_lossy(&cmd.stdout).to_string(),
+            stderr: String::from_utf8_lossy(&cmd.stderr).to_string(),
+        };
+
+        if cmd.status.success() {
+            Ok(output)
+        } else {
+            Err(output)
+        }
    }

    pub fn state(&self) -> State {
@@ -121,6 +240,11 @@ impl Display for Exercise {
    }
 }

+#[inline]
+fn clean() {
+    let _ignored = remove_file(&temp_file());
+}
+
 #[cfg(test)]
 mod test {
    use super::*;
@@ -131,11 +255,12 @@ mod test {
        File::create(&temp_file()).unwrap();
        let exercise = Exercise {
            name: String::from("example"),
-            path: PathBuf::from("example.rs"),
-            mode: Mode::Test,
+            path: PathBuf::from("tests/fixture/state/pending_exercise.rs"),
+            mode: Mode::Compile,
            hint: String::from(""),
        };
-        exercise.clean();
+        let compiled = exercise.compile().unwrap();
+        drop(compiled);
        assert!(!Path::new(&temp_file()).exists());
    }

@@ -191,4 +316,16 @@ mod test {

        assert_eq!(exercise.state(), State::Done);
    }
+
+    #[test]
+    fn test_exercise_with_output() {
+        let exercise = Exercise {
+            name: "exercise_with_output".into(),
+            path: PathBuf::from("tests/fixture/success/testSuccess.rs"),
+            mode: Mode::Test,
+            hint: String::new(),
+        };
+        let out = exercise.compile().unwrap().run().unwrap();
+        assert!(out.stdout.contains("THIS TEST TOO SHALL PASS"));
+    }
 }
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,15 +2,22 @@ use crate::exercise::{Exercise, ExerciseList};
 use crate::run::run;
 use crate::verify::verify;
 use clap::{crate_version, App, Arg, SubCommand};
+use console::Emoji;
 use notify::DebouncedEvent;
 use notify::{RecommendedWatcher, RecursiveMode, Watcher};
 use std::ffi::OsStr;
 use std::fs;
+use std::io;
 use std::path::Path;
 use std::process::{Command, Stdio};
 use std::sync::mpsc::channel;
+use std::sync::{Arc, Mutex};
+use std::thread;
 use std::time::Duration;

+#[macro_use]
+mod ui;
+
 mod exercise;
 mod run;
 mod verify;
@@ -20,8 +27,21 @@ fn main() {
        .version(crate_version!())
        .author("Olivia Hugger, Carol Nichols")
        .about("Rustlings is a collection of small exercises to get you used to writing and reading Rust code")
-        .subcommand(SubCommand::with_name("verify").alias("v").about("Verifies all exercises according to the recommended order"))
-        .subcommand(SubCommand::with_name("watch").alias("w").about("Reruns `verify` when files were edited"))
+        .arg(
+            Arg::with_name("nocapture")
+                .long("nocapture")
+                .help("Show outputs from the test exercises")
+        )
+        .subcommand(
+            SubCommand::with_name("verify")
+                .alias("v")
+                .about("Verifies all exercises according to the recommended order")
+        )
+        .subcommand(
+            SubCommand::with_name("watch")
+                .alias("w")
+                .about("Reruns `verify` when files were edited")
+        )
        .subcommand(
            SubCommand::with_name("run")
                .alias("r")
@@ -36,7 +56,7 @@ fn main() {
        )
        .get_matches();

-    if None == matches.subcommand_name() {
+    if matches.subcommand_name().is_none() {
        println!();
        println!(r#"       welcome to...                      "#);
        println!(r#"                 _   _ _                  "#);
@@ -66,6 +86,7 @@ fn main() {

    let toml_str = &fs::read_to_string("info.toml").unwrap();
    let exercises = toml::from_str::<ExerciseList>(toml_str).unwrap().exercises;
+    let verbose = matches.is_present("nocapture");

    if let Some(ref matches) = matches.subcommand_matches("run") {
        let name = matches.value_of("name").unwrap();
@@ -77,7 +98,7 @@ fn main() {
            std::process::exit(1)
        });

-        run(&exercise).unwrap_or_else(|_| std::process::exit(1));
+        run(&exercise, verbose).unwrap_or_else(|_| std::process::exit(1));
    }

    if let Some(ref matches) = matches.subcommand_matches("hint") {
@@ -95,11 +116,26 @@ fn main() {
    }

    if matches.subcommand_matches("verify").is_some() {
-        verify(&exercises).unwrap_or_else(|_| std::process::exit(1));
+        verify(&exercises, verbose).unwrap_or_else(|_| std::process::exit(1));
    }

    if matches.subcommand_matches("watch").is_some() {
-        watch(&exercises).unwrap();
+        if let Err(e) = watch(&exercises, verbose) {
+            println!("Error: Could not watch your progess. Error message was {:?}.", e);
+            println!("Most likely you've run out of disk space or your 'inotify limit' has been reached.");
+            std::process::exit(1);
+        }
+        println!(
+            "{emoji} All exercises completed! {emoji}",
+            emoji = Emoji("🎉", "★")
+        );
+        println!();
+        println!("We hope you enjoyed learning about the various aspects of Rust!");
+        println!("If you noticed any issues, please don't hesitate to report them to our repo.");
+        println!("You can also contribute your own exercises to help the greater community!");
+        println!();
+        println!("Before reporting an issue or contributing, please read our guidelines:");
+        println!("https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md");
    }

    if matches.subcommand_name().is_none() {
@@ -108,7 +144,30 @@ fn main() {
    }
 }

-fn watch(exercises: &[Exercise]) -> notify::Result<()> {
+fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
+    let failed_exercise_hint = Arc::clone(failed_exercise_hint);
+    println!("Type 'hint' to get help or 'clear' to clear the screen");
+    thread::spawn(move || loop {
+        let mut input = String::new();
+        match io::stdin().read_line(&mut input) {
+            Ok(_) => {
+                let input = input.trim();
+                if input.eq("hint") {
+                    if let Some(hint) = &*failed_exercise_hint.lock().unwrap() {
+                        println!("{}", hint);
+                    }
+                } else if input.eq("clear") {
+                    println!("\x1B[2J\x1B[1;1H");
+                } else {
+                    println!("unknown command: {}", input);
+                }
+            }
+            Err(error) => println!("error reading command: {}", error),
+        }
+    });
+}
+
+fn watch(exercises: &[Exercise], verbose: bool) -> notify::Result<()> {
    /* Clears the terminal with an ANSI escape code.
    Works in UNIX and newer Windows terminals. */
    fn clear_screen() {
@@ -121,8 +180,13 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
    watcher.watch(Path::new("./exercises"), RecursiveMode::Recursive)?;

    clear_screen();
-    let _ignored = verify(exercises.iter());

+    let to_owned_hint = |t: &Exercise| t.hint.to_owned();
+    let failed_exercise_hint = match verify(exercises.iter(), verbose) {
+        Ok(_) => return Ok(()),
+        Err(exercise) => Arc::new(Mutex::new(Some(to_owned_hint(exercise)))),
+    };
+    spawn_watch_shell(&failed_exercise_hint);
    loop {
        match rx.recv() {
            Ok(event) => match event {
@@ -133,7 +197,13 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
                            .iter()
                            .skip_while(|e| !filepath.ends_with(&e.path));
                        clear_screen();
-                        let _ignored = verify(pending_exercises);
+                        match verify(pending_exercises, verbose) {
+                            Ok(_) => return Ok(()),
+                            Err(exercise) => {
+                                let mut failed_exercise_hint = failed_exercise_hint.lock().unwrap();
+                                *failed_exercise_hint = Some(to_owned_hint(exercise));
+                            }
+                        }
                    }
                }
                _ => {}
--- a/src/run.rs
+++ b/src/run.rs
@@ -1,52 +1,58 @@
 use crate::exercise::{Exercise, Mode};
 use crate::verify::test;
-use console::{style, Emoji};
 use indicatif::ProgressBar;

-pub fn run(exercise: &Exercise) -> Result<(), ()> {
+// Invoke the rust compiler on the path of the given exercise,
+// and run the ensuing binary.
+// The verbose argument helps determine whether or not to show
+// the output from the test harnesses (if the mode of the exercise is test)
+pub fn run(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
    match exercise.mode {
-        Mode::Test => test(exercise)?,
+        Mode::Test => test(exercise, verbose)?,
        Mode::Compile => compile_and_run(exercise)?,
+        Mode::Clippy => compile_and_run(exercise)?,
    }
    Ok(())
 }

-pub fn compile_and_run(exercise: &Exercise) -> Result<(), ()> {
+// Invoke the rust compiler on the path of the given exercise
+// and run the ensuing binary.
+// This is strictly for non-test binaries, so output is displayed
+fn compile_and_run(exercise: &Exercise) -> Result<(), ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);

-    let compilecmd = exercise.compile();
+    let compilation_result = exercise.compile();
+    let compilation = match compilation_result {
+        Ok(compilation) => compilation,
+        Err(output) => {
+            progress_bar.finish_and_clear();
+            warn!(
+                "Compilation of {} failed!, Compiler error message:\n",
+                exercise
+            );
+            println!("{}", output.stderr);
+            return Err(());
+        }
+    };
+
    progress_bar.set_message(format!("Running {}...", exercise).as_str());
-    if compilecmd.status.success() {
-        let runcmd = exercise.run();
-        progress_bar.finish_and_clear();
+    let result = compilation.run();
+    progress_bar.finish_and_clear();

-        if runcmd.status.success() {
-            println!("{}", String::from_utf8_lossy(&runcmd.stdout));
-            let formatstr = format!("{} Successfully ran {}", Emoji("✅", "✓"), exercise);
-            println!("{}", style(formatstr).green());
-            exercise.clean();
+    match result {
+        Ok(output) => {
+            println!("{}", output.stdout);
+            success!("Successfully ran {}", exercise);
            Ok(())
-        } else {
-            println!("{}", String::from_utf8_lossy(&runcmd.stdout));
-            println!("{}", String::from_utf8_lossy(&runcmd.stderr));
+        }
+        Err(output) => {
+            println!("{}", output.stdout);
+            println!("{}", output.stderr);

-            let formatstr = format!("{} Ran {} with errors", Emoji("⚠️ ", "!"), exercise);
-            println!("{}", style(formatstr).red());
-            exercise.clean();
+            warn!("Ran {} with errors", exercise);
            Err(())
        }
-    } else {
-        progress_bar.finish_and_clear();
-        let formatstr = format!(
-            "{} Compilation of {} failed! Compiler error message:\n",
-            Emoji("⚠️ ", "!"),
-            exercise
-        );
-        println!("{}", style(formatstr).red());
-        println!("{}", String::from_utf8_lossy(&compilecmd.stderr));
-        exercise.clean();
-        Err(())
    }
 }
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -0,0 +1,23 @@
+macro_rules! warn {
+    ($fmt:literal, $ex:expr) => {{
+        use console::{style, Emoji};
+        let formatstr = format!($fmt, $ex);
+        println!(
+            "{} {}",
+            style(Emoji("⚠️ ", "!")).red(),
+            style(formatstr).red()
+        );
+    }};
+}
+
+macro_rules! success {
+    ($fmt:literal, $ex:expr) => {{
+        use console::{style, Emoji};
+        let formatstr = format!($fmt, $ex);
+        println!(
+            "{} {}",
+            style(Emoji("✅", "✓")).green(),
+            style(formatstr).green()
+        );
+    }};
+}
--- a/src/verify.rs
+++ b/src/verify.rs
@@ -1,96 +1,137 @@
-use crate::exercise::{Exercise, Mode, State};
-use console::{style, Emoji};
+use crate::exercise::{CompiledExercise, Exercise, Mode, State};
+use console::style;
 use indicatif::ProgressBar;

-pub fn verify<'a>(start_at: impl IntoIterator<Item = &'a Exercise>) -> Result<(), ()> {
+// Verify that the provided container of Exercise objects
+// can be compiled and run without any failures.
+// Any such failures will be reported to the end user.
+// If the Exercise being verified is a test, the verbose boolean
+// determines whether or not the test harness outputs are displayed.
+pub fn verify<'a>(
+    start_at: impl IntoIterator<Item = &'a Exercise>,
+    verbose: bool,
+) -> Result<(), &'a Exercise> {
    for exercise in start_at {
-        let is_done = match exercise.mode {
-            Mode::Test => compile_and_test_interactively(&exercise)?,
-            Mode::Compile => compile_only(&exercise)?,
+        let compile_result = match exercise.mode {
+            Mode::Test => compile_and_test(&exercise, RunMode::Interactive, verbose),
+            Mode::Compile => compile_and_run_interactively(&exercise),
+            Mode::Clippy => compile_only(&exercise),
        };
-        if !is_done {
-            return Err(());
+        if !compile_result.unwrap_or(false) {
+            return Err(exercise);
        }
    }
    Ok(())
 }

-pub fn test(exercise: &Exercise) -> Result<(), ()> {
-    compile_and_test(exercise, true)?;
+enum RunMode {
+    Interactive,
+    NonInteractive,
+}
+
+// Compile and run the resulting test harness of the given Exercise
+pub fn test(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
+    compile_and_test(exercise, RunMode::NonInteractive, verbose)?;
    Ok(())
 }

+// Invoke the rust compiler without running the resulting binary
 fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
-    let compile_output = exercise.compile();
+
+    let _ = compile(&exercise, &progress_bar)?;
    progress_bar.finish_and_clear();
-    if compile_output.status.success() {
-        let formatstr = format!("{} Successfully compiled {}!", Emoji("✅", "✓"), exercise);
-        println!("{}", style(formatstr).green());
-        exercise.clean();
-        Ok(prompt_for_completion(&exercise))
-    } else {
-        let formatstr = format!(
-            "{} Compilation of {} failed! Compiler error message:\n",
-            Emoji("⚠️ ", "!"),
-            exercise
-        );
-        println!("{}", style(formatstr).red());
-        println!("{}", String::from_utf8_lossy(&compile_output.stderr));
-        exercise.clean();
-        Err(())
-    }
+
+    success!("Successfully compiled {}!", exercise);
+    Ok(prompt_for_completion(&exercise, None))
 }

-fn compile_and_test_interactively(exercise: &Exercise) -> Result<bool, ()> {
-    compile_and_test(exercise, false)
+// Compile the given Exercise and run the resulting binary in an interactive mode
+fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
+    let progress_bar = ProgressBar::new_spinner();
+    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
+    progress_bar.enable_steady_tick(100);
+
+    let compilation = compile(&exercise, &progress_bar)?;
+
+    progress_bar.set_message(format!("Running {}...", exercise).as_str());
+    let result = compilation.run();
+    progress_bar.finish_and_clear();
+
+    let output = match result {
+        Ok(output) => output,
+        Err(output) => {
+            warn!("Ran {} with errors", exercise);
+            println!("{}", output.stdout);
+            println!("{}", output.stderr);
+            return Err(());
+        }
+    };
+
+    success!("Successfully ran {}!", exercise);
+
+    Ok(prompt_for_completion(&exercise, Some(output.stdout)))
 }

-fn compile_and_test(exercise: &Exercise, skip_prompt: bool) -> Result<bool, ()> {
+// Compile the given Exercise as a test harness and display
+// the output if verbose is set to true
+fn compile_and_test(exercise: &Exercise, run_mode: RunMode, verbose: bool) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Testing {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);

-    let compile_output = exercise.compile();
-    if compile_output.status.success() {
-        progress_bar.set_message(format!("Running {}...", exercise).as_str());
+    let compilation = compile(exercise, &progress_bar)?;
+    let result = compilation.run();
+    progress_bar.finish_and_clear();

-        let runcmd = exercise.run();
-        progress_bar.finish_and_clear();
-
-        if runcmd.status.success() {
-            let formatstr = format!("{} Successfully tested {}!", Emoji("✅", "✓"), exercise);
-            println!("{}", style(formatstr).green());
-            exercise.clean();
-            Ok(skip_prompt || prompt_for_completion(exercise))
-        } else {
-            let formatstr = format!(
-                "{} Testing of {} failed! Please try again. Here's the output:",
-                Emoji("⚠️ ", "!"),
+    match result {
+        Ok(output) => {
+            if verbose {
+                println!("{}", output.stdout);
+            }
+            success!("Successfully tested {}", &exercise);
+            if let RunMode::Interactive = run_mode {
+                Ok(prompt_for_completion(&exercise, None))
+            } else {
+                Ok(true)
+            }
+        }
+        Err(output) => {
+            warn!(
+                "Testing of {} failed! Please try again. Here's the output:",
                exercise
            );
-            println!("{}", style(formatstr).red());
-            println!("{}", String::from_utf8_lossy(&runcmd.stdout));
-            exercise.clean();
+            println!("{}", output.stdout);
            Err(())
        }
-    } else {
-        progress_bar.finish_and_clear();
-        let formatstr = format!(
-            "{} Compiling of {} failed! Please try again. Here's the output:",
-            Emoji("⚠️ ", "!"),
-            exercise
-        );
-        println!("{}", style(formatstr).red());
-        println!("{}", String::from_utf8_lossy(&compile_output.stderr));
-        exercise.clean();
-        Err(())
    }
 }

-fn prompt_for_completion(exercise: &Exercise) -> bool {
+// Compile the given Exercise and return an object with information
+// about the state of the compilation
+fn compile<'a, 'b>(
+    exercise: &'a Exercise,
+    progress_bar: &'b ProgressBar,
+) -> Result<CompiledExercise<'a>, ()> {
+    let compilation_result = exercise.compile();
+
+    match compilation_result {
+        Ok(compilation) => Ok(compilation),
+        Err(output) => {
+            progress_bar.finish_and_clear();
+            warn!(
+                "Compiling of {} failed! Please try again. Here's the output:",
+                exercise
+            );
+            println!("{}", output.stderr);
+            Err(())
+        }
+    }
+}
+
+fn prompt_for_completion(exercise: &Exercise, prompt_output: Option<String>) -> bool {
    let context = match exercise.state() {
        State::Done => return true,
        State::Pending(context) => context,
@@ -99,22 +140,32 @@ fn prompt_for_completion(exercise: &Exercise) -> bool {
    let success_msg = match exercise.mode {
        Mode::Compile => "The code is compiling!",
        Mode::Test => "The code is compiling, and the tests pass!",
+        Mode::Clippy => "The code is compiling, and 📎 Clippy 📎 is happy!",
    };

-    println!("");
+    println!();
    println!("🎉 🎉  {} 🎉 🎉", success_msg);
-    println!("");
+    println!();
+
+    if let Some(output) = prompt_output {
+        println!("Output:");
+        println!("{}", separator());
+        println!("{}", output);
+        println!("{}", separator());
+        println!();
+    }
+
    println!("You can keep working on this exercise,");
    println!(
        "or jump into the next one by removing the {} comment:",
        style("`I AM NOT DONE`").bold()
    );
-    println!("");
+    println!();
    for context_line in context {
        let formatted_line = if context_line.important {
            format!("{}", style(context_line.line).bold())
        } else {
-            format!("{}", context_line.line)
+            context_line.line.to_string()
        };

        println!(
@@ -127,3 +178,7 @@ fn prompt_for_completion(exercise: &Exercise) -> bool {

    false
 }
+
+fn separator() -> console::StyledObject<&'static str> {
+    style("====================").bold()
+}
--- a/tests/fixture/success/testSuccess.rs
+++ b/tests/fixture/success/testSuccess.rs
@@ -1,4 +1,5 @@
 #[test]
 fn passing() {
+    println!("THIS TEST TOO SHALL PASS");
    assert!(true);
 }
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -31,7 +31,7 @@ fn verify_all_success() {
 }

 #[test]
-fn verify_all_failure() {
+fn verify_fails_if_some_fails() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .arg("v")
@@ -159,3 +159,25 @@ fn run_test_exercise_does_not_prompt() {
        .code(0)
        .stdout(predicates::str::contains("I AM NOT DONE").not());
 }
+
+#[test]
+fn run_single_test_success_with_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["--nocapture", "r", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS"));
+}
+
+#[test]
+fn run_single_test_success_without_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["r", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS").not());
+}