chore: Release

Updated name of variable name in hint

CHANGELOG.md

@@ -1,3 +1,22 @@
+<a name="6.1.0"></a>
+
+## 6.1.0 (2024-07-10)
+
+#### Added
+
+- `dev check`: Check that all exercises (including third-party ones) include at least one `TODO` comment.
+- `dev check`: Check that all exercises actually fail to run (not already solved).
+
+#### Changed
+
+- Make enum variants more consistent between enum exercises.
+- `iterators3`: Teach about the possible case of integer overflow during division.
+
+#### Fixed
+
+- Exit with a helpful error message on missing/unsupported terminal/TTY.
+- Mark the last exercise as done.
+
 <a name="6.0.1"></a>
 
 ## 6.0.1 (2024-07-04)
@@ -64,7 +83,7 @@ This should avoid issues related to the language server or to running exercises,
 Clippy lints are now shown on all exercises, not only the Clippy exercises 📎
 Make Clippy your friend from early on 🥰
 
-### Third party exercises
+### Third-party exercises
 
 Rustlings now supports third-party exercises!
 

Cargo.lock

@@ -151,9 +151,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clap"
-version = "4.5.8"
+version = "4.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "84b3edb18336f4df585bc9aa31dd99c036dfa5dc5e9a2939a722a188f3a8970d"
+checksum = "64acc1846d54c1fe936a78dc189c34e28d3f5afc348403f28ecf53660b9b8462"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -161,9 +161,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.8"
+version = "4.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1c09dd5ada6c6c78075d6fd0da3f90d8080651e2d6cc8eb2f1aaa4034ced708"
+checksum = "6fb8393d67ba2e7bfaf28a23458e4e2b543cc73a99595511eb207fdb8aede942"
 dependencies = [
  "anstream",
  "anstyle",
@@ -354,15 +354,6 @@ version = "1.70.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8478577c03552c21db0e2724ffb8986a5ce7af88107e6be5d2ee6e158c12800"
 
-[[package]]
-name = "itertools"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba291022dbbd398a455acf126c1e341954079855bc60dfdda641363bd6922569"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "itertools"
 version = "0.13.0"
@@ -594,7 +585,7 @@ dependencies = [
  "cassowary",
  "compact_str",
  "crossterm",
- "itertools 0.13.0",
+ "itertools",
  "lru",
  "paste",
  "stability",
@@ -654,7 +645,7 @@ checksum = "7a66a03ae7c801facd77a29370b4faec201768915ac14a721ba36f20bc9c209b"
 
 [[package]]
 name = "rustlings"
-version = "6.0.1"
+version = "6.1.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
@@ -673,7 +664,7 @@ dependencies = [
 
 [[package]]
 name = "rustlings-macros"
-version = "6.0.1"
+version = "6.1.0"
 dependencies = [
  "quote",
  "serde",
@@ -709,18 +700,18 @@ checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
 name = "serde"
-version = "1.0.203"
+version = "1.0.204"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
+checksum = "bc76f558e0cbb2a839d37354c575f1dc3fdc6546b5be373ba43d95f231bf7c12"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.203"
+version = "1.0.204"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "500cbc0ebeb6f46627f50f3f5811ccf6bf00643be300b4c3eabc0ef55dc5b5ba"
+checksum = "e0cd7e117be63d3c3678776753929474f3b04a43a080c744d6b0ae2a8c28e222"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -785,9 +776,9 @@ checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
 
 [[package]]
 name = "stability"
-version = "0.2.0"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2ff9eaf853dec4c8802325d8b6d3dffa86cc707fd7a1a4cdbf416e13b061787a"
+checksum = "d904e7009df136af5297832a3ace3370cd14ff1546a232f4f185036c2736fcac"
 dependencies = [
  "quote",
  "syn",
@@ -829,9 +820,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.68"
+version = "2.0.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "901fa70d88b9d6c98022e23b4136f9f3e54e4662c3bc1bd1d84a42a9a0f0c1e9"
+checksum = "2f0209b68b3613b093e0ec905354eccaedcfe83b8cb37cbdeae64026c3064c16"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -855,9 +846,9 @@ dependencies = [
 
 [[package]]
 name = "toml_edit"
-version = "0.22.14"
+version = "0.22.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f21c7aaf97f1bd9ca9d4f9e73b0a6c74bd5afef56f2bc931943a6e1c37e04e38"
+checksum = "d59a3a72298453f564e2b111fa896f8d07fabb36f51f06d7e875fc5e0b5a3ef1"
 dependencies = [
  "indexmap",
  "serde",
@@ -880,11 +871,12 @@ checksum = "d4c87d22b6e3f4a18d4d40ef354e97c90fcb14dd91d7dc0aa9d8a1172ebf7202"
 
 [[package]]
 name = "unicode-truncate"
-version = "1.0.0"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a5fbabedabe362c618c714dbefda9927b5afc8e2a8102f47f081089a9019226"
+checksum = "b3644627a5af5fa321c95b9b235a72fd24cd29c648c2c379431e6628655627bf"
 dependencies = [
- "itertools 0.12.1",
+ "itertools",
+ "unicode-segmentation",
  "unicode-width",
 ]
 

Cargo.toml

@@ -8,7 +8,7 @@ exclude = [
 ]
 
 [workspace.package]
-version = "6.0.1"
+version = "6.1.0"
 authors = [
   "Liv <mokou@fastmail.com>",
   "Mo Bitar <mo8it@proton.me>",
@@ -20,8 +20,8 @@ license = "MIT"
 edition = "2021"
 
 [workspace.dependencies]
-serde = { version = "1.0.203", features = ["derive"] }
-toml_edit = { version = "0.22.14", default-features = false, features = ["parse", "serde"] }
+serde = { version = "1.0.204", features = ["derive"] }
+toml_edit = { version = "0.22.15", default-features = false, features = ["parse", "serde"] }
 
 [package]
 name = "rustlings"
@@ -47,13 +47,13 @@ include = [
 
 [dependencies]
 anyhow = "1.0.86"
-clap = { version = "4.5.8", features = ["derive"] }
+clap = { version = "4.5.9", features = ["derive"] }
 crossterm = "0.27.0"
 hashbrown = "0.14.5"
 notify-debouncer-mini = { version = "0.4.1", default-features = false }
 os_pipe = "1.2.0"
 ratatui = { version = "0.27.0", default-features = false, features = ["crossterm"] }
-rustlings-macros = { path = "rustlings-macros", version = "=6.0.1" }
+rustlings-macros = { path = "rustlings-macros", version = "=6.1.0" }
 serde_json = "1.0.120"
 serde.workspace = true
 toml_edit.workspace = true

README.md

@@ -19,7 +19,7 @@ It contains code examples and exercises similar to Rustlings, but online.
 
 Before installing Rustlings, you need to have _Rust installed_.
 Visit [www.rust-lang.org/tools/install](https://www.rust-lang.org/tools/install) for further instructions on installing Rust.
-This'll also install _Cargo_, Rust's package/project manager.
+This will also install _Cargo_, Rust's package/project manager.
 
 > 🐧 If you're on Linux, make sure you've installed `gcc` (for a linker).
 >
@@ -124,7 +124,7 @@ Continue practicing your Rust skills by building your own projects, contributing
 
 Do you want to create your own set of Rustlings exercises to focus on some specific topic?
 Or do you want to translate the original Rustlings exercises?
-Then follow the link to the guide about [third-party exercises](THIRD_PARTY_EXERCISES.md)!
+Then follow the link to the guide about [third-party exercises](https://github.com/rust-lang/rustlings/blob/main/THIRD_PARTY_EXERCISES.md)!
 
 ## Uninstalling Rustlings
 

THIRD_PARTY_EXERCISES.md

@@ -1,7 +1,7 @@
 # Third-Party Exercises
 
 The support of Rustlings for third-party exercises allows you to create your own set of Rustlings exercises to focus on some specific topic.
-You could also offer a translatation of the original Rustlings exercises as third-party exercises.
+You could also offer a translation of the original Rustlings exercises as third-party exercises.
 
 ## Getting started
 

dev/rustlings-repo.txt

@@ -1 +1 @@
-This file is used to check if the user tries to run Rustlings in the repository (the method before v6)
+This file is used to check if the user tries to run Rustlings in the repository (the method before version 6)

exercises/04_primitive_types/README.md

@@ -5,5 +5,5 @@ compiler. In this section, we'll go through the most important ones.
 
 ## Further information
 
-- [Data Types](https://doc.rust-lang.org/stable/book/ch03-02-data-types.html)
-- [The Slice Type](https://doc.rust-lang.org/stable/book/ch04-03-slices.html)
+- [Data Types](https://doc.rust-lang.org/book/ch03-02-data-types.html)
+- [The Slice Type](https://doc.rust-lang.org/book/ch04-03-slices.html)

exercises/05_vecs/README.md

@@ -12,6 +12,6 @@ the other useful data structure, hash maps, later.
 
 ## Further information
 
-- [Storing Lists of Values with Vectors](https://doc.rust-lang.org/stable/book/ch08-01-vectors.html)
+- [Storing Lists of Values with Vectors](https://doc.rust-lang.org/book/ch08-01-vectors.html)
 - [`iter_mut`](https://doc.rust-lang.org/std/primitive.slice.html#method.iter_mut)
 - [`map`](https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.map)

exercises/06_move_semantics/move_semantics4.rs

@@ -7,12 +7,12 @@ mod tests {
     // TODO: Fix the compiler errors only by reordering the lines in the test.
     // Don't add, change or remove any line.
     #[test]
-    fn move_semantics5() {
-        let mut x = 100;
+    fn move_semantics4() {
+        let mut x = Vec::new();
         let y = &mut x;
         let z = &mut x;
-        *y += 100;
-        *z += 1000;
-        assert_eq!(x, 1200);
+        y.push(42);
+        z.push(13);
+        assert_eq!(x, [42, 13]);
     }
 }

exercises/06_move_semantics/move_semantics5.rs

@@ -3,14 +3,6 @@
 // TODO: Fix the compiler errors without changing anything except adding or
 // removing references (the character `&`).
 
-fn main() {
-    let data = "Rust is great!".to_string();
-
-    get_char(data);
-
-    string_uppercase(&data);
-}
-
 // Shouldn't take ownership
 fn get_char(data: String) -> char {
     data.chars().last().unwrap()
@@ -22,3 +14,11 @@ fn string_uppercase(mut data: &String) {
 
     println!("{data}");
 }
+
+fn main() {
+    let data = "Rust is great!".to_string();
+
+    get_char(data);
+
+    string_uppercase(&data);
+}

exercises/07_structs/structs3.rs

@@ -1,5 +1,5 @@
-// Structs contain data, but can also have logic. In this exercise we have
-// defined the `Package` struct and we want to test some logic attached to it.
+// Structs contain data, but can also have logic. In this exercise, we have
+// defined the `Package` struct, and we want to test some logic attached to it.
 
 #[derive(Debug)]
 struct Package {

exercises/08_enums/enums1.rs

@@ -4,8 +4,9 @@ enum Message {
 }
 
 fn main() {
-    println!("{:?}", Message::Quit);
-    println!("{:?}", Message::Echo);
+    println!("{:?}", Message::Resize);
     println!("{:?}", Message::Move);
+    println!("{:?}", Message::Echo);
     println!("{:?}", Message::ChangeColor);
+    println!("{:?}", Message::Quit);
 }

exercises/08_enums/enums2.rs

@@ -1,4 +1,11 @@
-#[allow(dead_code)]
+#![allow(dead_code)]
+
+#[derive(Debug)]
+struct Point {
+    x: u64,
+    y: u64,
+}
+
 #[derive(Debug)]
 enum Message {
     // TODO: Define the different variants used below.
@@ -12,7 +19,11 @@ impl Message {
 
 fn main() {
     let messages = [
-        Message::Move { x: 10, y: 30 },
+        Message::Resize {
+            width: 10,
+            height: 30,
+        },
+        Message::Move(Point { x: 10, y: 15 }),
         Message::Echo(String::from("hello world")),
         Message::ChangeColor(200, 255, 255),
         Message::Quit,

exercises/08_enums/enums3.rs

@@ -1,40 +1,47 @@
+struct Point {
+    x: u64,
+    y: u64,
+}
+
 enum Message {
     // TODO: Implement the message variant types based on their usage below.
 }
 
-struct Point {
-    x: u8,
-    y: u8,
-}
-
 struct State {
-    color: (u8, u8, u8),
+    width: u64,
+    height: u64,
     position: Point,
-    quit: bool,
     message: String,
+    // RGB color composed of red, green and blue.
+    color: (u8, u8, u8),
+    quit: bool,
 }
 
 impl State {
-    fn change_color(&mut self, color: (u8, u8, u8)) {
-        self.color = color;
-    }
-
-    fn quit(&mut self) {
-        self.quit = true;
-    }
-
-    fn echo(&mut self, s: String) {
-        self.message = s;
+    fn resize(&mut self, width: u64, height: u64) {
+        self.width = width;
+        self.height = height;
     }
 
     fn move_position(&mut self, point: Point) {
         self.position = point;
     }
 
+    fn echo(&mut self, s: String) {
+        self.message = s;
+    }
+
+    fn change_color(&mut self, red: u8, green: u8, blue: u8) {
+        self.color = (red, green, blue);
+    }
+
+    fn quit(&mut self) {
+        self.quit = true;
+    }
+
     fn process(&mut self, message: Message) {
-        // TODO: Create a match expression to process the different message variants.
-        // Remember: When passing a tuple as a function argument, you'll need extra parentheses:
-        // e.g. `foo((t, u, p, l, e))`
+        // TODO: Create a match expression to process the different message
+        // variants using the methods defined above.
     }
 }
 
@@ -49,21 +56,29 @@ mod tests {
     #[test]
     fn test_match_message_call() {
         let mut state = State {
-            quit: false,
+            width: 0,
+            height: 0,
             position: Point { x: 0, y: 0 },
-            color: (0, 0, 0),
             message: String::from("hello world"),
+            color: (0, 0, 0),
+            quit: false,
         };
 
-        state.process(Message::ChangeColor(255, 0, 255));
-        state.process(Message::Echo(String::from("Hello world!")));
+        state.process(Message::Resize {
+            width: 10,
+            height: 30,
+        });
         state.process(Message::Move(Point { x: 10, y: 15 }));
+        state.process(Message::Echo(String::from("Hello world!")));
+        state.process(Message::ChangeColor(255, 0, 255));
         state.process(Message::Quit);
 
-        assert_eq!(state.color, (255, 0, 255));
+        assert_eq!(state.width, 10);
+        assert_eq!(state.height, 30);
         assert_eq!(state.position.x, 10);
         assert_eq!(state.position.y, 15);
-        assert!(state.quit);
         assert_eq!(state.message, "Hello world!");
+        assert_eq!(state.color, (255, 0, 255));
+        assert!(state.quit);
     }
 }

exercises/09_strings/strings4.rs

@@ -4,6 +4,7 @@ fn placeholder() {}
 fn string_slice(arg: &str) {
     println!("{arg}");
 }
+
 fn string(arg: String) {
     println!("{arg}");
 }

exercises/11_hashmaps/hashmaps2.rs

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

exercises/12_options/README.md

@@ -14,7 +14,7 @@ Option types are very common in Rust code, as they have a number of uses:
 
 ## Further Information
 
-- [Option Enum Format](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-enum-definitions)
+- [Option Enum Format](https://doc.rust-lang.org/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)
 - [if let](https://doc.rust-lang.org/rust-by-example/flow_control/if_let.html)

exercises/13_error_handling/errors3.rs

@@ -19,6 +19,7 @@ fn main() {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
+    // Don't change this line.
     let cost = total_cost(pretend_user_input)?;
 
     if cost > tokens {

exercises/13_error_handling/errors5.rs

@@ -39,8 +39,8 @@ struct PositiveNonzeroInteger(u64);
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         match value {
-            0 => Err(CreationError::Zero),
             x if x < 0 => Err(CreationError::Negative),
+            0 => Err(CreationError::Zero),
             x => Ok(PositiveNonzeroInteger(x as u64)),
         }
     }

exercises/14_generics/README.md

@@ -7,5 +7,5 @@ The simplest and most common use of generics is for type parameters.
 
 ## Further information
 
-- [Generic Data Types](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html)
+- [Generic Data Types](https://doc.rust-lang.org/book/ch10-01-syntax.html)
 - [Bounds](https://doc.rust-lang.org/rust-by-example/generics/bounds.html)

exercises/18_iterators/iterators3.rs

@@ -1,12 +1,16 @@
 #[derive(Debug, PartialEq, Eq)]
 enum DivisionError {
+    // Example: 42 / 0
     DivideByZero,
+    // Only case for `i64`: `i64::MIN / -1` because the result is `i64::MAX + 1`
+    IntegerOverflow,
+    // Example: 5 / 2 = 2.5
     NotDivisible,
 }
 
 // TODO: Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
 // Otherwise, return a suitable error.
-fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+fn divide(a: i64, b: i64) -> Result<i64, DivisionError> {
     todo!();
 }
 
@@ -42,6 +46,11 @@ mod tests {
         assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
     }
 
+    #[test]
+    fn test_integer_overflow() {
+        assert_eq!(divide(i64::MIN, -1), Err(DivisionError::IntegerOverflow));
+    }
+
     #[test]
     fn test_not_divisible() {
         assert_eq!(divide(81, 6), Err(DivisionError::NotDivisible));

exercises/18_iterators/iterators4.rs

@@ -1,5 +1,8 @@
-fn factorial(num: u8) -> u64 {
-    // TODO: Complete this function to return the factorial of `num`.
+fn factorial(num: u64) -> u64 {
+    // TODO: Complete this function to return the factorial of `num` which is
+    // defined as `1 * 2 * 3 * … * num`.
+    // https://en.wikipedia.org/wiki/Factorial
+    //
     // Do not use:
     // - early returns (using the `return` keyword explicitly)
     // Try not to use:

exercises/19_smart_pointers/cow1.rs

@@ -45,8 +45,9 @@ mod tests {
     #[test]
     fn owned_no_mutation() {
         // We can also pass `vec` without `&` so `Cow` owns it directly. In this
-        // case, no mutation occurs and thus also no clone. But the result is
-        // still owned because it was never borrowed or mutated.
+        // case, no mutation occurs (all numbers are already absolute) and thus
+        // also no clone. But the result is still owned because it was never
+        // borrowed or mutated.
         let vec = vec![0, 1, 2];
         let mut input = Cow::from(vec);
         abs_all(&mut input);
@@ -56,9 +57,9 @@ mod tests {
 
     #[test]
     fn owned_mutation() {
-        // Of course this is also the case if a mutation does occur. In this
-        // case, the call to `to_mut()` in the `abs_all` function returns a
-        // reference to the same data as before.
+        // Of course this is also the case if a mutation does occur (not all
+        // numbers are absolute). In this case, the call to `to_mut()` in the
+        // `abs_all` function returns a reference to the same data as before.
         let vec = vec![-1, 0, 1];
         let mut input = Cow::from(vec);
         abs_all(&mut input);

exercises/quizzes/quiz1.rs

@@ -5,12 +5,12 @@
 //
 // Mary is buying apples. The price of an apple is calculated as follows:
 // - An apple costs 2 rustbucks.
-// - If Mary buys more than 40 apples, each apple only costs 1 rustbuck!
+// - However, if Mary buys more than 40 apples, the price of each apple in the
+// entire order is reduced to only 1 rustbuck!
+
 // TODO: Write a function that calculates the price of an order of apples given
 // the quantity bought.
-
-// Put your function here!
-// fn calculate_price_of_apples(???) -> ??? {
+// fn calculate_price_of_apples(???) -> ??? { ??? }
 
 fn main() {
     // You can optionally experiment here.

rustlings-macros/info.toml

@@ -31,6 +31,7 @@ https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md"""
 name = "intro1"
 dir = "00_intro"
 test = false
+skip_check_unsolved = true
 hint = """
 Enter `n` to move on to the next exercise.
 You might need to press ENTER after typing `n`."""
@@ -308,7 +309,7 @@ In Rust, there are two ways to define a Vector.
    inside the square brackets. This way is simpler when you exactly know
    the initial values.
 
-Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
+Check this chapter: https://doc.rust-lang.org/book/ch08-01-vectors.html
 of the Rust book to learn more."""
 
 [[exercises]]
@@ -350,7 +351,7 @@ We call this "moving" a variable. When we pass `vec0` into `fill_vec`, it's
 being "moved" into `vec1`, meaning we can't access `vec0` anymore.
 
 You could make another, separate version of the data that's in `vec0` and
-pass it to `fill_vec` instead."""
+pass it to `fill_vec` instead. This is called cloning in Rust."""
 
 [[exercises]]
 name = "move_semantics3"
@@ -377,7 +378,7 @@ dir = "06_move_semantics"
 test = false
 hint = """
 To find the answer, you can consult the book section "References and Borrowing":
-https://doc.rust-lang.org/stable/book/ch04-02-references-and-borrowing.html
+https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html
 
 The first problem is that `get_char` is taking ownership of the string. So
 `data` is moved and can't be used for `string_uppercase`. `data` is moved to
@@ -415,7 +416,7 @@ to its fields.
 
 There are 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"""
+https://doc.rust-lang.org/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax"""
 
 [[exercises]]
 name = "structs3"
@@ -444,7 +445,7 @@ dir = "08_enums"
 test = false
 hint = """
 You can create enumerations that have different variants with different types
-such as no data, anonymous structs, a single string, tuples, etc."""
+such as anonymous structs, structs, a single string, tuples, no data, etc."""
 
 [[exercises]]
 name = "enums3"
@@ -486,7 +487,7 @@ to add one character to the `if` statement, though, that will coerce the
 Side note: If you're interested in learning about how this kind of reference
 conversion works, you can jump ahead in the book and read this part in the
 smart pointers chapter:
-https://doc.rust-lang.org/stable/book/ch15-02-deref.html#implicit-deref-coercions-with-functions-and-methods"""
+https://doc.rust-lang.org/book/ch15-02-deref.html#implicit-deref-coercions-with-functions-and-methods"""
 
 [[exercises]]
 name = "strings3"
@@ -560,7 +561,7 @@ hint = """
 Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
 
 Learn more in The Book:
-https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value"""
+https://doc.rust-lang.org/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value"""
 
 [[exercises]]
 name = "hashmaps3"
@@ -571,7 +572,7 @@ Hint 1: Use the `entry()` and `or_insert()` (or `or_insert_with()`) methods of
         exist in the table yet.
 
 Learn more in The Book:
-https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
+https://doc.rust-lang.org/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
 
 Hint 2: If there is already an entry for a given key, the value returned by
         `entry()` can be updated based on the existing value.
@@ -584,7 +585,7 @@ https://doc.rust-lang.org/book/ch08-03-hash-maps.html#updating-a-value-based-on-
 [[exercises]]
 name = "quiz2"
 dir = "quizzes"
-hint = "No hints this time ;)"
+hint = "The `+` operator can concatenate a `String` with a `&str`."
 
 # OPTIONS
 
@@ -738,7 +739,7 @@ name = "generics2"
 dir = "14_generics"
 hint = """
 Related section in The Book:
-https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions"""
+https://doc.rust-lang.org/book/ch10-01-syntax.html#in-method-definitions"""
 
 # TRAITS
 
@@ -747,7 +748,9 @@ name = "traits1"
 dir = "15_traits"
 hint = """
 More about traits in The Book:
-https://doc.rust-lang.org/book/ch10-02-traits.html"""
+https://doc.rust-lang.org/book/ch10-02-traits.html
+
+The `+` operator can concatenate a `String` with a `&str`."""
 
 [[exercises]]
 name = "traits2"
@@ -868,7 +871,7 @@ We expect the method `Rectangle::new` to panic for negative values.
 To handle that, you need to add a special attribute to the test function.
 
 You can refer to the docs:
-https://doc.rust-lang.org/stable/book/ch11-01-writing-tests.html#checking-for-panics-with-should_panic"""
+https://doc.rust-lang.org/book/ch11-01-writing-tests.html#checking-for-panics-with-should_panic"""
 
 # STANDARD LIBRARY TYPES
 
@@ -887,9 +890,9 @@ hint = """
 `capitalize_first`:
 
 The variable `first` is a `char`. It needs to be capitalized and added to the
-remaining characters in `c` in order to return the correct `String`.
+remaining characters in `chars` in order to return the correct `String`.
 
-The remaining characters in `c` can be viewed as a string slice using the
+The remaining characters in `chars` can be viewed as a string slice using the
 `as_str` method.
 
 The documentation for `char` contains many useful methods.
@@ -1004,7 +1007,7 @@ thread-local copy of the numbers.
 This is a simple exercise if you understand the underlying concepts, but if this
 is too much of a struggle, consider reading through all of Chapter 16 in The
 Book:
-https://doc.rust-lang.org/stable/book/ch16-00-concurrency.html"""
+https://doc.rust-lang.org/book/ch16-00-concurrency.html"""
 
 [[exercises]]
 name = "cow1"
@@ -1142,7 +1145,11 @@ test = false
 strict_clippy = true
 hint = """
 `for` loops over `Option` values are more clearly expressed as an `if-let`
-statement."""
+statement.
+
+Not required to solve this exercise, but if you are interested in when iterating
+over `Option` can be useful, read the following section in the documentation:
+https://doc.rust-lang.org/std/option/#iterating-over-option"""
 
 [[exercises]]
 name = "clippy3"

solutions/06_move_semantics/move_semantics4.rs

@@ -7,15 +7,15 @@ mod tests {
     // TODO: Fix the compiler errors only by reordering the lines in the test.
     // Don't add, change or remove any line.
     #[test]
-    fn move_semantics5() {
-        let mut x = 100;
+    fn move_semantics4() {
+        let mut x = Vec::new();
         let y = &mut x;
         // `y` used here.
-        *y += 100;
+        y.push(42);
         // The mutable reference `y` is not used anymore,
         // therefore a new reference can be created.
         let z = &mut x;
-        *z += 1000;
-        assert_eq!(x, 1200);
+        z.push(13);
+        assert_eq!(x, [42, 13]);
     }
 }

solutions/06_move_semantics/move_semantics5.rs

@@ -1,13 +1,5 @@
 #![allow(clippy::ptr_arg)]
 
-fn main() {
-    let data = "Rust is great!".to_string();
-
-    get_char(&data);
-
-    string_uppercase(data);
-}
-
 // Borrows instead of taking ownership.
 // It is recommended to use `&str` instead of `&String` here. But this is
 // enough for now because we didn't handle strings yet.
@@ -21,3 +13,11 @@ fn string_uppercase(mut data: String) {
 
     println!("{data}");
 }
+
+fn main() {
+    let data = "Rust is great!".to_string();
+
+    get_char(&data);
+
+    string_uppercase(data);
+}

solutions/08_enums/enums1.rs

@@ -1,14 +1,16 @@
 #[derive(Debug)]
 enum Message {
-    Quit,
-    Echo,
+    Resize,
     Move,
+    Echo,
     ChangeColor,
+    Quit,
 }
 
 fn main() {
-    println!("{:?}", Message::Quit);
-    println!("{:?}", Message::Echo);
+    println!("{:?}", Message::Resize);
     println!("{:?}", Message::Move);
+    println!("{:?}", Message::Echo);
     println!("{:?}", Message::ChangeColor);
+    println!("{:?}", Message::Quit);
 }

solutions/08_enums/enums2.rs

@@ -1,7 +1,15 @@
-#[allow(dead_code)]
+#![allow(dead_code)]
+
+#[derive(Debug)]
+struct Point {
+    x: u64,
+    y: u64,
+}
+
 #[derive(Debug)]
 enum Message {
-    Move { x: i64, y: i64 },
+    Resize { width: u64, height: u64 },
+    Move(Point),
     Echo(String),
     ChangeColor(u8, u8, u8),
     Quit,
@@ -15,7 +23,11 @@ impl Message {
 
 fn main() {
     let messages = [
-        Message::Move { x: 10, y: 30 },
+        Message::Resize {
+            width: 10,
+            height: 30,
+        },
+        Message::Move(Point { x: 10, y: 15 }),
         Message::Echo(String::from("hello world")),
         Message::ChangeColor(200, 255, 255),
         Message::Quit,

solutions/08_enums/enums3.rs

@@ -1,44 +1,53 @@
+struct Point {
+    x: u64,
+    y: u64,
+}
+
 enum Message {
-    ChangeColor(u8, u8, u8),
-    Echo(String),
+    Resize { width: u64, height: u64 },
     Move(Point),
+    Echo(String),
+    ChangeColor(u8, u8, u8),
     Quit,
 }
 
-struct Point {
-    x: u8,
-    y: u8,
-}
-
 struct State {
-    color: (u8, u8, u8),
+    width: u64,
+    height: u64,
     position: Point,
-    quit: bool,
     message: String,
+    color: (u8, u8, u8),
+    quit: bool,
 }
 
 impl State {
-    fn change_color(&mut self, color: (u8, u8, u8)) {
-        self.color = color;
-    }
-
-    fn quit(&mut self) {
-        self.quit = true;
-    }
-
-    fn echo(&mut self, s: String) {
-        self.message = s;
+    fn resize(&mut self, width: u64, height: u64) {
+        self.width = width;
+        self.height = height;
     }
 
     fn move_position(&mut self, point: Point) {
         self.position = point;
     }
 
+    fn echo(&mut self, s: String) {
+        self.message = s;
+    }
+
+    fn change_color(&mut self, red: u8, green: u8, blue: u8) {
+        self.color = (red, green, blue);
+    }
+
+    fn quit(&mut self) {
+        self.quit = true;
+    }
+
     fn process(&mut self, message: Message) {
         match message {
-            Message::ChangeColor(r, g, b) => self.change_color((r, g, b)),
-            Message::Echo(s) => self.echo(s),
+            Message::Resize { width, height } => self.resize(width, height),
             Message::Move(point) => self.move_position(point),
+            Message::Echo(s) => self.echo(s),
+            Message::ChangeColor(r, g, b) => self.change_color(r, g, b),
             Message::Quit => self.quit(),
         }
     }
@@ -55,21 +64,29 @@ mod tests {
     #[test]
     fn test_match_message_call() {
         let mut state = State {
-            quit: false,
+            width: 0,
+            height: 0,
             position: Point { x: 0, y: 0 },
-            color: (0, 0, 0),
             message: String::from("hello world"),
+            color: (0, 0, 0),
+            quit: false,
         };
 
-        state.process(Message::ChangeColor(255, 0, 255));
-        state.process(Message::Echo(String::from("Hello world!")));
+        state.process(Message::Resize {
+            width: 10,
+            height: 30,
+        });
         state.process(Message::Move(Point { x: 10, y: 15 }));
+        state.process(Message::Echo(String::from("Hello world!")));
+        state.process(Message::ChangeColor(255, 0, 255));
         state.process(Message::Quit);
 
-        assert_eq!(state.color, (255, 0, 255));
+        assert_eq!(state.width, 10);
+        assert_eq!(state.height, 30);
         assert_eq!(state.position.x, 10);
         assert_eq!(state.position.y, 15);
-        assert!(state.quit);
         assert_eq!(state.message, "Hello world!");
+        assert_eq!(state.color, (255, 0, 255));
+        assert!(state.quit);
     }
 }

solutions/09_strings/strings4.rs

@@ -1,6 +1,7 @@
 fn string_slice(arg: &str) {
     println!("{arg}");
 }
+
 fn string(arg: String) {
     println!("{arg}");
 }

solutions/18_iterators/iterators3.rs

@@ -1,6 +1,10 @@
 #[derive(Debug, PartialEq, Eq)]
 enum DivisionError {
+    // Example: 42 / 0
     DivideByZero,
+    // Only case for `i64`: `i64::MIN / -1` because the result is `i64::MAX + 1`
+    IntegerOverflow,
+    // Example: 5 / 2 = 2.5
     NotDivisible,
 }
 
@@ -9,6 +13,10 @@ fn divide(a: i64, b: i64) -> Result<i64, DivisionError> {
         return Err(DivisionError::DivideByZero);
     }
 
+    if a == i64::MIN && b == -1 {
+        return Err(DivisionError::IntegerOverflow);
+    }
+
     if a % b != 0 {
         return Err(DivisionError::NotDivisible);
     }
@@ -51,6 +59,11 @@ mod tests {
         assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
     }
 
+    #[test]
+    fn test_integer_overflow() {
+        assert_eq!(divide(i64::MIN, -1), Err(DivisionError::IntegerOverflow));
+    }
+
     #[test]
     fn test_not_divisible() {
         assert_eq!(divide(81, 6), Err(DivisionError::NotDivisible));

solutions/18_iterators/iterators5.rs

@@ -47,6 +47,23 @@ fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Pr
         .sum()
 }
 
+// Equivalent to `count_collection_iterator` and `count_iterator`, iterating as
+// if the collection was a single container instead of a container of containers
+// (and more accurately, a single iterator instead of an iterator of iterators).
+fn count_collection_iterator_flat(
+    collection: &[HashMap<String, Progress>],
+    value: Progress,
+) -> usize {
+    // `collection` is a slice of hash maps.
+    // collection = [{ "variables1": Complete, "from_str": None, … },
+    //               { "variables2": Complete, … }, … ]
+    collection
+        .iter()
+        .flat_map(HashMap::values) // or just `.flatten()` when wanting the default iterator (`HashMap::iter`)
+        .filter(|val| **val == value)
+        .count()
+}
+
 fn main() {
     // You can optionally experiment here.
 }
@@ -54,10 +71,9 @@ fn main() {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use Progress::*;
 
     fn get_map() -> HashMap<String, Progress> {
-        use Progress::*;
-
         let mut map = HashMap::new();
         map.insert(String::from("variables1"), Complete);
         map.insert(String::from("functions1"), Complete);
@@ -70,8 +86,6 @@ mod tests {
     }
 
     fn get_vec_map() -> Vec<HashMap<String, Progress>> {
-        use Progress::*;
-
         let map = get_map();
 
         let mut other = HashMap::new();
@@ -87,25 +101,25 @@ mod tests {
     #[test]
     fn count_complete() {
         let map = get_map();
-        assert_eq!(count_iterator(&map, Progress::Complete), 3);
+        assert_eq!(count_iterator(&map, Complete), 3);
     }
 
     #[test]
     fn count_some() {
         let map = get_map();
-        assert_eq!(count_iterator(&map, Progress::Some), 1);
+        assert_eq!(count_iterator(&map, Some), 1);
     }
 
     #[test]
     fn count_none() {
         let map = get_map();
-        assert_eq!(count_iterator(&map, Progress::None), 2);
+        assert_eq!(count_iterator(&map, None), 2);
     }
 
     #[test]
     fn count_complete_equals_for() {
         let map = get_map();
-        let progress_states = [Progress::Complete, Progress::Some, Progress::None];
+        let progress_states = [Complete, Some, None];
         for progress_state in progress_states {
             assert_eq!(
                 count_for(&map, progress_state),
@@ -117,34 +131,38 @@ mod tests {
     #[test]
     fn count_collection_complete() {
         let collection = get_vec_map();
-        assert_eq!(
-            count_collection_iterator(&collection, Progress::Complete),
-            6,
-        );
+        assert_eq!(count_collection_iterator(&collection, Complete), 6);
+        assert_eq!(count_collection_iterator_flat(&collection, Complete), 6);
     }
 
     #[test]
     fn count_collection_some() {
         let collection = get_vec_map();
-        assert_eq!(count_collection_iterator(&collection, Progress::Some), 1);
+        assert_eq!(count_collection_iterator(&collection, Some), 1);
+        assert_eq!(count_collection_iterator_flat(&collection, Some), 1);
     }
 
     #[test]
     fn count_collection_none() {
         let collection = get_vec_map();
-        assert_eq!(count_collection_iterator(&collection, Progress::None), 4);
+        assert_eq!(count_collection_iterator(&collection, None), 4);
+        assert_eq!(count_collection_iterator_flat(&collection, None), 4);
     }
 
     #[test]
     fn count_collection_equals_for() {
         let collection = get_vec_map();
-        let progress_states = [Progress::Complete, Progress::Some, Progress::None];
+        let progress_states = [Complete, Some, None];
 
         for progress_state in progress_states {
             assert_eq!(
                 count_collection_for(&collection, progress_state),
                 count_collection_iterator(&collection, progress_state),
             );
+            assert_eq!(
+                count_collection_for(&collection, progress_state),
+                count_collection_iterator_flat(&collection, progress_state),
+            );
         }
     }
 }

solutions/19_smart_pointers/cow1.rs

@@ -45,8 +45,9 @@ mod tests {
     #[test]
     fn owned_no_mutation() {
         // We can also pass `vec` without `&` so `Cow` owns it directly. In this
-        // case, no mutation occurs and thus also no clone. But the result is
-        // still owned because it was never borrowed or mutated.
+        // case, no mutation occurs (all numbers are already absolute) and thus
+        // also no clone. But the result is still owned because it was never
+        // borrowed or mutated.
         let vec = vec![0, 1, 2];
         let mut input = Cow::from(vec);
         abs_all(&mut input);
@@ -56,9 +57,9 @@ mod tests {
 
     #[test]
     fn owned_mutation() {
-        // Of course this is also the case if a mutation does occur. In this
-        // case, the call to `to_mut()` in the `abs_all` function returns a
-        // reference to the same data as before.
+        // Of course this is also the case if a mutation does occur (not all
+        // numbers are absolute). In this case, the call to `to_mut()` in the
+        // `abs_all` function returns a reference to the same data as before.
         let vec = vec![-1, 0, 1];
         let mut input = Cow::from(vec);
         abs_all(&mut input);

solutions/23_conversions/as_ref_mut.rs

@@ -15,7 +15,7 @@ fn char_counter<T: AsRef<str>>(arg: T) -> usize {
 // Squares a number using `as_mut()`.
 fn num_sq<T: AsMut<u32>>(arg: &mut T) {
     let arg = arg.as_mut();
-    *arg = *arg * *arg;
+    *arg *= *arg;
 }
 
 fn main() {

solutions/quizzes/quiz1.rs

@@ -1,8 +1,7 @@
 // Mary is buying apples. The price of an apple is calculated as follows:
 // - An apple costs 2 rustbucks.
-// - If Mary buys more than 40 apples, each apple only costs 1 rustbuck!
-// Write a function that calculates the price of an order of apples given the
-// quantity bought.
+// - However, if Mary buys more than 40 apples, the price of each apple in the
+// entire order is reduced to only 1 rustbuck!
 
 fn calculate_price_of_apples(n_apples: u64) -> u64 {
     if n_apples > 40 {

solutions/quizzes/quiz2.rs

@@ -1,10 +1,3 @@
-// This is a quiz for the following sections:
-// - Strings
-// - Vecs
-// - Move semantics
-// - Modules
-// - Enums
-//
 // Let's build a little machine in the form of a function. As input, we're going
 // to give a list of strings and commands. These commands determine what action
 // is going to be applied to the string. It can either be:
@@ -13,7 +6,7 @@
 // - Append "bar" to the string a specified amount of times
 //
 // The exact form of this will be:
-// - The input is going to be a vector of a 2-length tuple,
+// - The input is going to be a vector of 2-length tuples,
 //   the first element is the string, the second one is the command.
 // - The output element is going to be a vector of strings.
 
@@ -31,17 +24,12 @@ mod my_module {
     pub fn transformer(input: Vec<(String, Command)>) -> Vec<String> {
         let mut output = Vec::new();
 
-        for (mut string, command) in input {
+        for (string, command) in input {
             // Create the new string.
             let new_string = match command {
                 Command::Uppercase => string.to_uppercase(),
                 Command::Trim => string.trim().to_string(),
-                Command::Append(n) => {
-                    for _ in 0..n {
-                        string += "bar";
-                    }
-                    string
-                }
+                Command::Append(n) => string + &"bar".repeat(n),
             };
 
             // Push the new string to the output vector.
@@ -56,15 +44,10 @@ mod my_module {
     pub fn transformer_iter(input: Vec<(String, Command)>) -> Vec<String> {
         input
             .into_iter()
-            .map(|(mut string, command)| match command {
+            .map(|(string, command)| match command {
                 Command::Uppercase => string.to_uppercase(),
                 Command::Trim => string.trim().to_string(),
-                Command::Append(n) => {
-                    for _ in 0..n {
-                        string += "bar";
-                    }
-                    string
-                }
+                Command::Append(n) => string + &"bar".repeat(n),
             })
             .collect()
     }

solutions/quizzes/quiz3.rs

@@ -1,7 +1,3 @@
-// This quiz tests:
-// - Generics
-// - Traits
-//
 // 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

src/app_state.rs

@@ -403,6 +403,9 @@ impl AppState {
             writeln!(writer, "{}", "ok".green())?;
         }
 
+        // Write that the last exercise is done.
+        self.write()?;
+
         clear_terminal(writer)?;
         writer.write_all(FENISH_LINE.as_bytes())?;
 

src/cargo_toml.rs

@@ -111,6 +111,7 @@ mod tests {
                 test: true,
                 strict_clippy: true,
                 hint: String::new(),
+                skip_check_unsolved: false,
             },
             ExerciseInfo {
                 name: String::from("2"),
@@ -118,6 +119,7 @@ mod tests {
                 test: false,
                 strict_clippy: false,
                 hint: String::new(),
+                skip_check_unsolved: false,
             },
         ];
 

src/dev/check.rs

@@ -92,6 +92,10 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
             bail!("The `main` function is missing in the file `{path}`.\nCreate at least an empty `main` function to avoid language server errors");
         }
 
+        if !file_buf.contains("// TODO") {
+            bail!("Didn't find any `// TODO` comment in the file `{path}`.\nYou need to have at least one such comment to guide the user.");
+        }
+
         if !exercise_info.test && file_buf.contains("#[test]") {
             bail!("The file `{path}` contains tests annotated with `#[test]` but the exercise `{name}` has `test = false` in the `info.toml` file");
         }
@@ -158,7 +162,46 @@ fn check_unexpected_files(
     Ok(())
 }
 
-fn check_exercises(info_file: &InfoFile) -> Result<()> {
+fn check_exercises_unsolved(info_file: &InfoFile, target_dir: &Path) -> Result<()> {
+    let error_occurred = AtomicBool::new(false);
+
+    println!(
+        "Running all exercises to check that they aren't already solved. This may take a while…\n",
+    );
+    thread::scope(|s| {
+        for exercise_info in &info_file.exercises {
+            if exercise_info.skip_check_unsolved {
+                continue;
+            }
+
+            s.spawn(|| {
+                let error = |e| {
+                    let mut stderr = io::stderr().lock();
+                    stderr.write_all(e).unwrap();
+                    stderr.write_all(b"\nProblem with the exercise ").unwrap();
+                    stderr.write_all(exercise_info.name.as_bytes()).unwrap();
+                    stderr.write_all(SEPARATOR).unwrap();
+                    error_occurred.store(true, atomic::Ordering::Relaxed);
+                };
+
+                let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
+                match exercise_info.run_exercise(&mut output, target_dir) {
+                    Ok(true) => error(b"Already solved!"),
+                    Ok(false) => (),
+                    Err(e) => error(e.to_string().as_bytes()),
+                }
+            });
+        }
+    });
+
+    if error_occurred.load(atomic::Ordering::Relaxed) {
+        bail!(CHECK_EXERCISES_UNSOLVED_ERR);
+    }
+
+    Ok(())
+}
+
+fn check_exercises(info_file: &InfoFile, target_dir: &Path) -> Result<()> {
     match info_file.format_version.cmp(&CURRENT_FORMAT_VERSION) {
         Ordering::Less => bail!("`format_version` < {CURRENT_FORMAT_VERSION} (supported version)\nPlease migrate to the latest format version"),
         Ordering::Greater => bail!("`format_version` > {CURRENT_FORMAT_VERSION} (supported version)\nTry updating the Rustlings program"),
@@ -168,15 +211,14 @@ fn check_exercises(info_file: &InfoFile) -> Result<()> {
     let info_file_paths = check_info_file_exercises(info_file)?;
     check_unexpected_files("exercises", &info_file_paths)?;
 
-    Ok(())
+    check_exercises_unsolved(info_file, target_dir)
 }
 
-fn check_solutions(require_solutions: bool, info_file: &InfoFile) -> Result<()> {
-    let target_dir = parse_target_dir()?;
+fn check_solutions(require_solutions: bool, info_file: &InfoFile, target_dir: &Path) -> Result<()> {
     let paths = Mutex::new(hashbrown::HashSet::with_capacity(info_file.exercises.len()));
     let error_occurred = AtomicBool::new(false);
 
-    println!("Running all solutions. This may take a while...\n");
+    println!("Running all solutions. This may take a while…\n");
     thread::scope(|s| {
         for exercise_info in &info_file.exercises {
             s.spawn(|| {
@@ -202,7 +244,7 @@ fn check_solutions(require_solutions: bool, info_file: &InfoFile) -> Result<()>
                 }
 
                 let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-                match exercise_info.run_solution(&mut output, &target_dir) {
+                match exercise_info.run_solution(&mut output, target_dir) {
                     Ok(true) => {
                         paths.lock().unwrap().insert(PathBuf::from(path));
                     }
@@ -238,8 +280,9 @@ pub fn check(require_solutions: bool) -> Result<()> {
         check_cargo_toml(&info_file.exercises, &current_cargo_toml, b"")?;
     }
 
-    check_exercises(&info_file)?;
-    check_solutions(require_solutions, &info_file)?;
+    let target_dir = parse_target_dir()?;
+    check_exercises(&info_file, &target_dir)?;
+    check_solutions(require_solutions, &info_file, &target_dir)?;
 
     println!("\nEverything looks fine!");
 
@@ -248,3 +291,6 @@ pub fn check(require_solutions: bool) -> Result<()> {
 
 const SEPARATOR: &[u8] =
     b"\n========================================================================================\n";
+
+const CHECK_EXERCISES_UNSOLVED_ERR: &str = "At least one exercise is already solved or failed to run. See the output above.
+If this is an intro exercise that is intended to be already solved, add `skip_check_unsolved = true` to the exercise's metadata in the `info.toml` file.";

src/dev/new.rs

@@ -139,7 +139,7 @@ const README: &str = "# Rustlings 🦀
 
 Welcome to these third-party Rustlings exercises 😃
 
-First, [install Rustlings using the official instructions in the README of the Rustlings project](https://github.com/rust-lang/rustlings) ✅
+First, [install Rustlings using the official instructions](https://github.com/rust-lang/rustlings) ✅
 
-Then, open your terminal in this directory and run `rustlings` to get started with the exercises 🚀
+Then, clone this repository, open a terminal in this directory and run `rustlings` to get started with the exercises 🚀
 ";

src/info_file.rs

@@ -11,14 +11,17 @@ pub struct ExerciseInfo {
     pub name: String,
     /// Exercise's directory name inside the `exercises/` directory.
     pub dir: Option<String>,
-    #[serde(default = "default_true")]
     /// Run `cargo test` on the exercise.
+    #[serde(default = "default_true")]
     pub test: bool,
     /// Deny all Clippy warnings.
     #[serde(default)]
     pub strict_clippy: bool,
     /// The exercise's hint to be shown to the user on request.
     pub hint: String,
+    /// The exercise is already solved. Ignore it when checking that all exercises are unsolved.
+    #[serde(default)]
+    pub skip_check_unsolved: bool,
 }
 #[inline(always)]
 const fn default_true() -> bool {

src/main.rs

@@ -2,7 +2,7 @@ use anyhow::{bail, Context, Result};
 use app_state::StateFileStatus;
 use clap::{Parser, Subcommand};
 use std::{
-    io::{self, BufRead, StdoutLock, Write},
+    io::{self, BufRead, IsTerminal, StdoutLock, Write},
     path::Path,
     process::exit,
 };
@@ -148,6 +148,10 @@ fn main() -> Result<()> {
 
     match args.command {
         None => {
+            if !io::stdout().is_terminal() {
+                bail!("Unsupported or missing terminal/TTY");
+            }
+
             let notify_exercise_names = if args.manual_run {
                 None
             } else {
@@ -197,9 +201,10 @@ fn main() -> Result<()> {
     Ok(())
 }
 
-const OLD_METHOD_ERR: &str = "You are trying to run Rustlings using the old method before v6.
+const OLD_METHOD_ERR: &str =
+    "You are trying to run Rustlings using the old method before version 6.
 The new method doesn't include cloning the Rustlings' repository.
-Please follow the instructions in the README:
+Please follow the instructions in `README.md`:
 https://github.com/rust-lang/rustlings#getting-started";
 
 const FORMAT_VERSION_HIGHER_ERR: &str =
@@ -216,5 +221,5 @@ const PRE_INIT_MSG: &str = r"
  |_|   \__,_|___/\__|_|_|_| |_|\__, |___/
                                |___/
 
-The `exercises` directory wasn't found in the current directory.
+The `exercises/` directory couldn't be found in the current directory.
 If you are just starting with Rustlings, run the command `rustlings init` to initialize it.";