Crate test_case

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test_case crate provides procedural macro attribute that generates parametrized test instances.

Getting Started

Crate has to be added as a dependency to Cargo.toml:

test-case = "3.1.0"

and imported to the scope of a block where it’s being called (since attribute name collides with rust’s built-in custom_test_frameworks) via:

use test_case::test_case;

Example usage:

mod tests {
    use test_case::test_case;

    #[test_case(-2, -4 ; "when both operands are negative")]
    #[test_case(2,  4  ; "when both operands are positive")]
    #[test_case(4,  2  ; "when operands are swapped")]
    fn multiplication_tests(x: i8, y: i8) {
        let actual = (x * y).abs();

        assert_eq!(8, actual)

Output from cargo test for this example:

$ cargo test

running 4 tests
test tests::multiplication_tests::when_both_operands_are_negative ... ok
test tests::multiplication_tests::when_both_operands_are_positive ... ok
test tests::multiplication_tests::when_operands_are_swapped ... ok

test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

MSRV Policy

Starting with version 3.0 and up test-case introduces policy of only supporting latest stable Rust. These changes may happen overnight, so if your stack is lagging behind current stable release, it may be best to consider locking test-case version with = in your Cargo.toml.


Most up to date documentation is available in our wiki.

Attribute Macros

  • Generates tests for given set of data
  • Generates tests for given set of data