13 - Testing

The uitest package tests FlowUI without opening a real window:

import "github.com/qianniancn/flowui/uitest"

Applications do not need uitest at runtime.

Widget harness

uitest.Harness drives layout frames, a fixed viewport, pointer and keyboard events, a controllable clock, and state cleanup:

func TestButtonClick(t *testing.T) {
    h := uitest.New(image.Pt(400, 300))
    clicked := false
    root := ui.Button("ok", ui.Text("OK")).OnClick(func() {
        clicked = true
    })

    // Layout a frame, inject a pointer event, and layout again.
    _ = h
    _ = root
    _ = clicked
}

Use stable keys and advance the harness clock for animation tests instead of sleeping. Prefer behavior assertions to screenshot-only tests.

Application harness

uitest.AppHarness exercises the production message queue, Update, command execution, error delivery, and close cancellation without creating a window. It is suited to testing loading success/failure and lifecycle behavior.

Test guidance

1. Test pure Update logic directly.
2. Use Harness for interaction, layout, and style states.
3. Use AppHarness for commands, subscriptions, and errors.
4. Use business IDs as keys so repeated controls retain the right state.
5. Keep external IO behind command boundaries and inject test doubles.

See the tests under uitest and the component tests under internal/components/*.