Unit Tests, Integration Tests, and Doctests

Unit Tests, Integration Tests, and Doctests

Rust has first-class built-in testing support.

Unit Tests

Unit tests live in the same source files as the code they test inside a #[cfg(test)] module:

pub 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);
    }
}

Integration Tests

Integration tests live in the top-level tests/ directory and test the public API as an external consumer.

Documentation Tests (Doctests)

Examples written in markdown doc-comments (///) are compiled and executed during cargo test.