# egui_kittest

Ui testing library for egui, based on [kittest](https://github.com/rerun-io/kittest) (an [AccessKit](https://github.com/AccessKit/accesskit) based testing library).

## Example usage
```rust
use egui::accesskit::Toggled;
use egui_kittest::{Harness, kittest::Queryable};

fn main() {
    let mut checked = false;
    let app = |ui: &mut egui::Ui| {
        ui.checkbox(&mut checked, "Check me!");
    };

    let mut harness = Harness::new_ui(app);

    let checkbox = harness.get_by_label("Check me!");
    assert_eq!(checkbox.toggled(), Some(Toggled::False));
    checkbox.click();

    harness.run();

    let checkbox = harness.get_by_label("Check me!");
    assert_eq!(checkbox.toggled(), Some(Toggled::True));

    // Shrink the window size to the smallest size possible
    harness.fit_contents();

    // You can even render the ui and do image snapshot tests
    #[cfg(all(feature = "wgpu", feature = "snapshot"))]
    harness.snapshot("readme_example");
}
```

## Snapshot testing
There is a snapshot testing feature. To create snapshot tests, enable the `snapshot` and `wgpu` features.
Once enabled, you can call `Harness::snapshot` to render the ui and save the image to the `tests/snapshots` directory.

To update the snapshots, run your tests with `UPDATE_SNAPSHOTS=true`, so e.g. `UPDATE_SNAPSHOTS=true cargo test`.
Running with `UPDATE_SNAPSHOTS=true` will cause the tests to succeed.
This is so that you can set `UPDATE_SNAPSHOTS=true` and update _all_ tests, without `cargo test` failing on the first failing crate.

If you want to have multiple snapshots in the same test, it makes sense to collect the results in a `Vec`
([look here](https://github.com/emilk/egui/blob/70a01138b77f9c5724a35a6ef750b9ae1ab9f2dc/crates/egui_demo_lib/src/demo/demo_app_windows.rs#L388-L427) for an example).
This way they can all be updated at the same time.

You should add the following to your `.gitignore`:
```gitignore
**/tests/snapshots/**/*.diff.png
**/tests/snapshots/**/*.new.png
```