Crate test_case

Overview

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:

[dev-dependencies]
test-case = "3.2.1"

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:

#[cfg(test)]
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

Test Matrix

The #[test_matrix(...)] macro allows generating multiple test cases from the Cartesian product of one or more possible values for each test function argument. The number of arguments to the test_matrix macro must be the same as the number of arguments to the test function. Each macro argument can be:

1. A list in array (`[x, y, ...]`) or tuple (`(x, y, ...)`) syntax. The values can be any
   valid [expression](https://doc.rust-lang.org/reference/expressions.html).
2. A closed numeric range expression (e.g. `0..100` or `1..=99`), which will generate
   argument values for all integers in the range.
3. A single expression, which can be used to keep one argument constant while varying the
   other test function arguments using a list or range.

Example usage:

#[cfg(test)]
mod tests {
    use test_case::test_matrix;

    #[test_matrix(
        [-2, 2],
        [-4, 4]
    )]
    fn multiplication_tests(x: i8, y: i8) {
        let actual = (x * y).abs();

        assert_eq!(8, actual)
    }
}

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.

Documentation

Most up to date documentation is available in our wiki.

Attribute Macros

• case
  Generates tests for given set of data
• test_case
  Generates tests for given set of data
• test_matrix
  Generates tests for the cartesian product of a given set of data