opening window crashes test suite

[aleferna12]

Hello, I get a fatal runtime error: Rust cannot catch foreign exceptions, aborting error when running this test on macOS Sequoia:

#[cfg(test)]
mod tests {
    #[test]
    fn test_window() {
        let window = minifb::Window::new(
            "test",
            100,
            100,
            minifb::WindowOptions::default()
        );
        assert!(window.is_ok());
    }
}

Full log is:

fatal runtime error: Rust cannot catch foreign exceptions, aborting
error: test failed, to rerun pass `-p evo-cpm --lib`

Caused by:
  process didn't exit successfully: `/Applications/RustRover.app/Contents/bin/native-helper/intellij-rust-native-helper /Users/aleferna/RustProjects/Projects/evo-cpm/target/debug/deps/evo_cpm-29137b184258c675 --format=json -Z unstable-options --show-output` (exit status: 102)
note: test exited abnormally; to see the full output pass --nocapture to the harness.
error: 1 target failed:
    `-p evo-cpm --lib`

Using --nocapture or RUST_BACKTRACE=1 give the same result, no extra information is added.

Running the same tests on windows and linux works no problem.

Minifb does actually work on my macos system though, which is puzzling. Its just the unit test that crashes.

[emoon]

Thanks for the report! I will have a look.

[AndreasOM]

Two fundamental problems:

Thread requirement

Rust's test harness spawns tests on worker threads, not the main thread. On macOS (and some other platforms), all GUI operations must run on the main thread. The OS enforces this via exceptions.

No event loop

Tests don't have a run loop/event loop, so GUI events can't be processed.

Solution:

You could use Objective-C runtime APIs to dispatch back to the main thread and start a run loop, but this is complex and platform-specific.

Recommendation:

Use examples as integration tests instead of #[test]. Examples run on the main thread naturally and work across all platforms.