t.Fatalf("timed out after %v waiting for child.Done(); stacks:\n%s", d, buf[:n])
	}
}

func TestLayersCancel(t *testing.T) {
	testLayers(t, time.Now().UnixNano(), false)
}

func TestLayersTimeout(t *testing.T) {
	testLayers(t, time.Now().UnixNano(), true)
}

func testLayers(t *testing.T, seed int64, testTimeout bool) {
	t.Parallel()

	r := rand.New(rand.NewSource(seed))