Unit Tests

Write unit tests with #[test] attribute.

Difficulty

Intermediate

Code

fn add(a: i32, b: i32) -> i32 {
    a + b
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_add() {
        assert_eq!(add(2, 3), 5);
    }

    #[test]
    fn test_add_negative() {
        assert_eq!(add(-1, 1), 0);
    }

    #[test]
    #[should_panic]
    fn test_panic() {
        panic!("expected panic");
    }
}

fn main() {
    println!("Run with: cargo test");
}

Explanation

This example demonstrates how to use unit tests in Rust. Read the code carefully to understand the flow. Pay attention to where values are created, borrowed, moved, or consumed.

Key Concepts

• Rust's strong type system catches errors at compile time
• Ownership and borrowing rules ensure memory safety
• Pattern matching makes code expressive and exhaustive

Related Topics

Browse more examples in the testing category to build a complete understanding of this topic.