Rustlings Topic: Tests

10 Feb 2022 in Study Log on Rust, Rustlings

Tests are Rust functions that verify that the non-test code is functioning in the expected manner. The bodies of test functions typically perform these three actions:

1. Set up any needed data or state.
2. Run the code you want to test.
3. Assert the results are what you expect.

Let’s look at the features Rust provides specifically for writing tests that take these actions, which include the test attribute, a few macros, and the should_panic attribute.

You may find solution code for the topic from my repo.

1. tests1.rs
2. tests2.rs
3. tests3.rs

tests1.rs

/* file: "exercises/tests/tests1.rs" */
#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert() {
        assert!(true);
    }
}

tests2.rs

/* file: "exercises/tests/tests2.rs" */
#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert_eq() {
        assert_eq!(String::from("Hi"), "Hi".to_string());
        let two = 2;
        assert_eq!(two, 2);
    }
}

tests3.rs

/* file: "exercises/tests/tests3.rs" */
pub fn is_even(num: i32) -> bool {
    num % 2 == 0
}

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

    #[test]
    fn is_true_when_even() {
        assert!(is_even(10));
    }

    #[test]
    fn is_false_when_odd() {
        assert!(!is_even(5));
    }
}

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