func myFunc() {
	time.Sleep(3 * time.Second)
	doSomething()
}

func myFunc(clock clockwork.Clock) {
	clock.Sleep(3 * time.Second)
	doSomething()
}

func TestMyFunc(t *testing.T) {
	ctx := context.Background()
	c := clockwork.NewFakeClock()
	// Start our sleepy function
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		myFunc(c)
		wg.Done()
	}()
	// Ensure we wait until myFunc is waiting on the clock.
	// Use a context to avoid blocking forever if something
	// goes wrong.
	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()
	c.BlockUntilContext(ctx, 1)
	assertState()
	// Advance the FakeClock forward in time
	c.Advance(3 * time.Second)
	// Wait until the function completes
	wg.Wait()
	assertState()
}

myFunc(clockwork.NewRealClock())