This crate is deprecated. Please use instead test-case

Test-case-derive has a couple of issues which I could not clean up due to lack of time. Fortunately, @frondeus forked it and resolved all of them. The most important differences:

1. The name does not contain missleading derive anymore. When I've created this crate, I didn't understand proc macros enough and added this unfortunate suffix without any real reason
2. It uses way newer syn and it does not work directly on tokens anymore
3. The syntax is slightly changed, :: is not in use anymore. Instead, ; delimits test case name now
4. It is possible to add attributes to your test cases, e.g. #[should_panic] or #[ignore]

Overview

This crate provides #[test_case] procedural macro attribute that generates multiple parametrized tests using one body with different input parameters. A test is generated for each data set passed in test_case attribute. Under the hood, all test cases that share same body are grouped into mod, giving clear and readable test results.

Documentation

Repository

Getting Started

First of all you have to add this dependency to your Cargo.toml:

[dev-dependencies]
test-case-derive = "0.2.0"

Additionally you have to enable proc_macro feature and include crate. You can do this globally by adding:

#![feature(proc_macro)]
extern crate test_case_derive;

to your lib.rs or main.rs file. Optionally you may enable proc macros only for tests:

#![cfg_attr(test, feature(proc_macro))]
#[cfg(test)]
extern crate test_case_derive;

Don't forget that procedural macros are imported with use statement:

use test_case_derive::test_case;

Example usage:

#![cfg(test)]
#![feature(proc_macro)]
extern crate test_case_derive;

use test_case_derive::test_case;

#[test_case( 2,  4 :: "when both operands are possitive")]
#[test_case( 4,  2 :: "when operands are swapped")]
#[test_case(-2, -4 :: "when both operands are negative")]
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 3 tests
test multiplication_tests::when_both_operands_are_possitive ... ok
test multiplication_tests::when_both_operands_are_negative ... ok
test multiplication_tests::when_operands_are_swapped ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

Examples

If your only assertion is just assert_eq!, you can pass the expectation as macro attribute using => syntax:

#[test_case( 2 => 2 :: "returns given number for positive input")]
#[test_case(-2 => 2 :: "returns opposite number for non-positive input")]
#[test_case( 0 => 0 :: "returns 0 for 0")]
fn abs_tests(x: i8) -> i8 {
   if x > 0 { x } else { -x }
}

Which is equivalent to

#[test_case( 2, 2 :: "returns given number for positive input")]
#[test_case(-2, 2 :: "returns opposite number for non-positive input")]
#[test_case( 0, 0 :: "returns 0 for 0")]
fn abs_tests(x: i8, expected: i8){
   let actual = if x > 0 { x } else { -x };

   assert_eq!(expected, actual);
}

Attributes and expectation may be any expresion unless they contain =>, e.g.

#[test_case(None,        None    => 0 :: "treats none as 0")]
#[test_case(Some(2),     Some(3) => 5)]
#[test_case(Some(2 + 3), Some(4) => 2 + 3 + 4)]
fn fancy_addition(x: Option<i8>, y: Option<i8>) -> i8 {
    x.unwrap_or(0) + y.unwrap_or(0)
}

Note: in fact, => is not prohibited but the parser will always treat last => sign as beginning of expectation definition.

Test case names are optional. They are set using :: followed by string literal at the end of macro attributes.

Example generated code:

mod fancy_addition {
    #[allow(unused_imports)]
    use super::*;

    fn fancy_addition(x: Option<i8>, y: Option<i8>) -> i8 {
        x.unwrap_or(0) + y.unwrap_or(0)
    }

    #[test]
    fn treats_none_as_0() {
        let expected = 0;
        let actual = fancy_addition(None, None);

        assert_eq!(expected, actual);
    }

    #[test]
    fn some_2_some_3() {
        let expected = 5;
        let actual = fancy_addition(Some(2), Some(3));

        assert_eq!(expected, actual);
    }

    #[test]
    fn some_2_3_some_4() {
        let expected = 2 + 3 + 4;
        let actual = fancy_addition(Some(2 + 3), Some(4));

        assert_eq!(expected, actual);
    }
}

Inconclusive (ignored) test cases (sicne 0.2.0)

If test case name (passed using :: syntax described above) contains word "inconclusive", generated test will be marked with #[ignore].

#[test_case("42")]
#[test_case("XX" :: "inconclusive - parsing letters temporarily doesn't work but it's ok")]
fn parses_input(input: &str) {
    // ...
}

Generated code:

mod parses_input {
    // ...

    #[test]
    pub fn _42() {
        // ...
    }

    #[test]
    #[ignore]
    pub fn inconclusive_parsing_letters_temporarily_doesn_t_work_but_it_s_ok() {
        // ...
    }

Note: word inconclusive is only reserved in test name given after ::.

Contribution

All contributions and comments are more than welcome! Don't be afraid to open an issue or PR whenever you find a bug or have an idea to improve this crate.

License

MIT License

Copyright (c) 2017 Marcin Sas-Szymański

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.