the unit type

challenges/challenges.json

@@ -107,6 +107,18 @@
     "created_at": "2024-06-10T00:00:00Z",
     "updated_at": "2024-06-10T00:00:00Z"
   },
+  {
+    "id": 30,
+    "title": "The Unit Type",
+    "slug": "the-unit-type",
+    "short_description": "Understand and use the unit type `()` in Rust.",
+    "language": "RUST",
+    "difficulty": "BEGINNER",
+    "track": "RUST_BASICS",
+    "tags": ["unit type", "basic operations"],
+    "created_at": "2024-06-10T00:00:00Z",
+    "updated_at": "2024-06-10T00:00:00Z"
+  },
   {
     "id": 2,
     "title": "Character counting string",

challenges/the-unit-type/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "the-unit-type"
+version = "0.1.0"
+edition = "2021"
+
+[dev-dependencies]
+syntest = { path = "../../crates/syntest" }

challenges/the-unit-type/description.md

@@ -0,0 +1,19 @@
+In Rust, the unit type `()` is a type that has exactly one value, also written as `()`. It is used to indicate the absence of a meaningful value and is often seen in functions that do not return a value.
+
+In this challenge, you will implement a function that prints a message and returns the unit type.
+
+## Your task
+
+You need to implement the function `print_message() -> ()` that prints `"Hello, Rust!"` to the console and returns the unit type.
+
+## Requirements
+
+- The `print_message` function should print `"Hello, Rust!"` to the console.
+- The function should return the unit type `()`.
+
+## Example
+
+```rust
+let result = print_message();
+assert_eq!(result, ());
+```

challenges/the-unit-type/src/lib.rs

@@ -0,0 +1,3 @@
+pub fn print_message() -> () {
+    println!("Hello, Rust!");
+}

challenges/the-unit-type/src/starter.rs

@@ -0,0 +1,3 @@
+pub fn print_message() -> () {
+    // TODO: Implement the function here
+}

challenges/the-unit-type/tests/tests.rs

@@ -0,0 +1,34 @@
+#[cfg(test)]
+mod tests {
+    use syntest::Syntest;
+    use the_unit_type::*;
+
+    #[test]
+    fn test_compiles() {
+        print_message();
+    }
+
+    #[test]
+    fn test_prints() {
+        let syntest = Syntest::new("print_message", "src/lib.rs");
+
+        let macros = syntest.mac.macros();
+
+        assert!(!macros.is_empty(), "You should use the `println!` macro");
+        assert_eq!(macros.len(), 1, "You should only print one message");
+
+        let macro_name = &macros[0].name;
+
+        assert_eq!(macro_name, "println", "You should use the `println!` macro");
+
+        for token in macros[0].tokens.iter() {
+            let token = token.to_lowercase();
+
+            assert_eq!(
+                (token.contains("hello"), token.contains("rust")),
+                (true, true),
+                "You should print `Hello, Rust!`"
+            )
+        }
+    }
+}