t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
	}
	if e := precanceledChild.Err(); e != Canceled {
		t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
	}
}

func XTestChildFinishesFirst(t testingT) {
	cancelable, stop := WithCancel(Background())
	defer stop()
	for _, parent := range []Context{Background(), cancelable} {
		child, cancel := WithCancel(parent)

		select {