release: 4.2.0

Co-authored-by: Volodymyr Patuta <6977238-fiplox@users.noreply.gitlab.com>

.all-contributorsrc

@@ -591,6 +591,52 @@
       "contributions": [
         "content"
       ]
+    },
+    {
+      "login": "ryanpcmcquen",
+      "name": "Ryan McQuen",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/772937?v=4",
+      "profile": "https://ryanpcmcquen.org",
+      "contributions": [
+        "code"
+      ]
+    },
+    {
+      "login": "AnnikaCodes",
+      "name": "Annika",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/56906084?v=4",
+      "profile": "https://github.com/AnnikaCodes",
+      "contributions": [
+        "review"
+      ]
+    },
+    {
+      "login": "darnuria",
+      "name": "Axel Viala",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/2827553?v=4",
+      "profile": "https://darnuria.eu",
+      "contributions": [
+        "code"
+      ]
+    },
+    {
+      "login": "sazid",
+      "name": "Mohammed Sazid Al Rashid",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/2370167?v=4",
+      "profile": "https://sazid.github.io",
+      "contributions": [
+        "content",
+        "code"
+      ]
+    },
+    {
+      "login": "seeplusplus",
+      "name": "Caleb Webber",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/17479099?v=4",
+      "profile": "https://codingthemsoftly.com",
+      "contributions": [
+        "maintenance"
+      ]
     }
   ],
   "contributorsPerLine": 8,

CHANGELOG.md

@@ -1,3 +1,24 @@
+<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)
 

Cargo.lock

@@ -592,7 +592,7 @@ dependencies = [
 
 [[package]]
 name = "rustlings"
-version = "4.1.0"
+version = "4.2.0"
 dependencies = [
  "assert_cmd 0.11.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rustlings"
-version = "4.1.0"
+version = "4.2.0"
 authors = ["Marisa <mokou@posteo.de>", "Carol (Nichols || Goulding) <carol.nichols@gmail.com>"]
 edition = "2018"
 

README.md

@@ -1,6 +1,6 @@
 ![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-63-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-68-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 # rustlings 🦀❤️ [![Build status](https://badge.buildkite.com/7af93d81dc522c67a1ec8e33ff5705861b1cb36360b774807f.svg)](https://buildkite.com/mokou/rustlings)
@@ -61,7 +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/4.1.0 # 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 .
 ```
 
@@ -226,6 +226,13 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <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>
 

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)

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);
+    }
+}

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);
+    }
+}

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));
+    }
+}

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>>()
+        );
+    }
+}

exercises/conversions/try_from_into.rs

@@ -4,7 +4,7 @@
 // You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
 use std::convert::{TryFrom, TryInto};
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 struct Color {
     red: u8,
     green: u8,
@@ -25,22 +25,19 @@ struct Color {
 // Tuple implementation
 impl TryFrom<(i16, i16, i16)> for Color {
     type Error = String;
-    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
-    }
+    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> {
-    }
+    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 try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
 }
 
 fn main() {
@@ -66,71 +63,93 @@ mod tests {
     use super::*;
 
     #[test]
-    #[should_panic]
     fn test_tuple_out_of_range_positive() {
-        let _ = Color::try_from((256, 1000, 10000)).unwrap();
+        assert!(Color::try_from((256, 1000, 10000)).is_err());
     }
     #[test]
-    #[should_panic]
     fn test_tuple_out_of_range_negative() {
-        let _ = Color::try_from((-1, -10, -256)).unwrap();
+        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: Color = (183, 65, 14).try_into().unwrap();
-        assert_eq!(c.red, 183);
-        assert_eq!(c.green, 65);
-        assert_eq!(c.blue, 14);
+        let c: Result<Color, String> = (183, 65, 14).try_into();
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
     }
-
     #[test]
-    #[should_panic]
     fn test_array_out_of_range_positive() {
-        let _: Color = [1000, 10000, 256].try_into().unwrap();
+        let c: Color = [1000, 10000, 256].try_into();
+        assert!(c.is_err());
     }
     #[test]
-    #[should_panic]
     fn test_array_out_of_range_negative() {
-        let _: Color = [-10, -256, -1].try_into().unwrap();
+        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: Color = [183, 65, 14].try_into().unwrap();
-        assert_eq!(c.red, 183);
-        assert_eq!(c.green, 65);
-        assert_eq!(c.blue, 14);
+        let c: Result<Color, String> = [183, 65, 14].try_into();
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
     }
-
     #[test]
-    #[should_panic]
     fn test_slice_out_of_range_positive() {
         let arr = [10000, 256, 1000];
-        let _ = Color::try_from(&arr[..]).unwrap();
+        assert!(Color::try_from(&arr[..]).is_err());
     }
     #[test]
-    #[should_panic]
     fn test_slice_out_of_range_negative() {
         let arr = [-256, -1, -10];
-        let _ = Color::try_from(&arr[..]).unwrap();
+        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 = Color::try_from(&v[..]).unwrap();
-        assert_eq!(c.red, 183);
-        assert_eq!(c.green, 65);
-        assert_eq!(c.blue, 14);
+        let c: Result<Color, String> = Color::try_from(&v[..]);
+        assert_eq!(
+            c,
+            Ok(Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            })
+        );
     }
     #[test]
-    #[should_panic]
     fn test_slice_excess_length() {
         let v = vec![0, 0, 0, 0];
-        let _ = Color::try_from(&v[..]).unwrap();
+        assert!(Color::try_from(&v[..]).is_err());
     }
     #[test]
-    #[should_panic]
     fn test_slice_insufficient_length() {
         let v = vec![0, 0];
-        let _ = Color::try_from(&v[..]).unwrap();
+        assert!(Color::try_from(&v[..]).is_err());
     }
 }

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!")
 }

exercises/standard_library_types/iterators2.rs

@@ -1,5 +1,5 @@
 // iterators2.rs
-// In this module, you'll learn some of unique advantages that iterators can offer.
+// 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.

exercises/tests/tests3.rs

@@ -20,7 +20,7 @@ mod tests {
     }
 
     #[test]
-    fn is_false_when_even() {
+    fn is_false_when_odd() {
         assert!();
     }
 }

info.toml

@@ -210,7 +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
@@ -370,6 +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]]

install.ps1

@@ -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'"

install.sh

@@ -87,7 +87,7 @@ function vercomp() {
 }
 
 RustVersion=$(rustc --version | cut -d " " -f 2)
-MinRustVersion=1.31
+MinRustVersion=1.39
 vercomp $RustVersion $MinRustVersion
 if [ $? -eq 2 ]
 then

src/exercise.rs

@@ -11,10 +11,15 @@ 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 to this process
+// 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.

src/main.rs

@@ -119,7 +119,12 @@ fn main() {
         verify(&exercises, verbose).unwrap_or_else(|_| std::process::exit(1));
     }
 
-    if matches.subcommand_matches("watch").is_some() && watch(&exercises, verbose).is_ok() {
+    if matches.subcommand_matches("watch").is_some() {
+        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("🎉", "★")