Attribute Macro test 

#[test]

#[gpui::test] can be used to annotate test functions that run with GPUI support.

It supports both synchronous and asynchronous tests, and can provide you with as many TestAppContext instances as you need. The output contains a #[test] annotation so this can be used with any existing test harness (cargo test or cargo-nextest).

#[gpui::test]
async fn test_foo(mut cx: &TestAppContext) { }

In addition to passing a TestAppContext, you can also ask for a StdRnd instance. this will be seeded with the SEED environment variable and is used internally by the ForegroundExecutor and BackgroundExecutor to run tasks deterministically in tests. Using the same StdRng for behavior in your test will allow you to exercise a wide variety of scenarios and interleavings just by changing the seed.

Arguments

• #[gpui::test] with no arguments runs once with the seed 0 or SEED env var if set.
• #[gpui::test(seed = 10)] runs once with the seed 10.
• #[gpui::test(seeds(10, 20, 30))] runs three times with seeds 10, 20, and 30.
• #[gpui::test(iterations = 5)] runs five times, providing as seed the values in the range 0..5.
• #[gpui::test(retries = 3)] runs up to four times if it fails to try and make it pass.
• #[gpui::test(on_failure = "crate::test::report_failure")] will call the specified function after the tests fail so that you can write out more detail about the failure.

You can combine iterations = ... with seeds(...):

• #[gpui::test(iterations = 5, seed = 10)] is equivalent to #[gpui::test(seeds(0, 1, 2, 3, 4, 10))].
• #[gpui::test(iterations = 5, seeds(10, 20, 30)] is equivalent to #[gpui::test(seeds(0, 1, 2, 3, 4, 10, 20, 30))].
• #[gpui::test(seeds(10, 20, 30), iterations = 5] is equivalent to #[gpui::test(seeds(0, 1, 2, 3, 4, 10, 20, 30))].

Environment Variables

• SEED: sets a seed for the first run
• ITERATIONS: forces the value of the iterations argument