Function Consistently

pkg/test/util/assert/assert.go:119–135

Consistently polls the fetch function for a duration and fails if the value ever changes from the expected value. Use sparingly to avoid flakiness, as this is inherently timing-dependent. This is useful for asserting that no events occur (e.g., that a value stays at 0). Default duration is 20ms with

(t test.Failer, fetch func() T, expected T, duration ...time.Duration)

// events occur (e.g., that a value stays at 0). Default duration is 20ms with
// 2ms polling interval.
func Consistently[T any](t test.Failer, fetch func() T, expected T, duration ...time.Duration) {
	t.Helper()
	d := time.Millisecond * 20
	if len(duration) > 0 {
		d = duration[0]
	}
	interval := time.Millisecond * 2
	deadline := time.Now().Add(d)

	for time.Now().Before(deadline) {
		a := fetch()
		if !cmp.Equal(a, expected, opts(expected)...) {
			t.Fatalf("value changed unexpectedly: %v\nGot: %v\nWant: %v", cmp.Diff(a, expected, opts(expected)...), a, expected)
		}
		time.Sleep(interval)
	}
}

// Error asserts the provided err is non-nil
func Error(t test.Failer, err error) {