rust
```cargo
[dependencies]
rstest = "0.19.0"
```
#[cfg(test)]
mod test {
use rstest::rstest;
#[rstest]
#[case("a", "a")]
#[case("b", "b")]
fn run_test(#[case] input: &str, #[case] expected: &str) {
let results = input;
assert_eq!(expected, input);
}
}