42.3 Running tests

Plain run:

cargo test

Use -- to separate arguments for the cargo test subcommand and the test application:

cargo test --help    # Help text of the cargo test subcommand
cargo test -- --help # Help text of the test application

By default multiple tests are run in parallel in threads. To disable parallelism, set the number of threads to one:

cargo test -- --test-threads=1

Print stdout also for passed tests:

cargo test -- --show-output

Run a subset of tests by name:

cargo test my_text

Only function whose name matches .*my_text.* will be run.

Ignore some tests by default:

#[cfg(test)]
mod tests {

    #[test]
    #[ignore]
    fn my_test() {
        // code that takes an hour to run
    }
}

To run ignored tests:

cargo test -- --ignored