// Test implementation
        }

        public boolean waitForNotification(long timeoutMs) throws InterruptedException {
            return notificationLatch.await(timeoutMs, TimeUnit.MILLISECONDS);
        }

        public WitnessNotification getLastNotification() {
            return lastNotification;
        }
    }

    /**

## 创建一个任务函数 { #create-a-task-function }

创建要作为后台任务运行的函数。

它只是一个可以接收参数的标准函数。

它可以是 `async def` 或普通的 `def` 函数，**FastAPI** 知道如何正确处理。

在这种情况下，任务函数将写入一个文件（模拟发送电子邮件）。

由于写操作不使用 `async` 和 `await`，我们用普通的 `def` 定义函数：

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[6:9] *}

## 添加后台任务 { #add-the-background-task }

在你的 *路径操作函数* 里，用 `.add_task()` 方法将任务函数传到 *后台任务* 对象中：

      },
    )
    assertThat(server.takeRequest().exchangeIndex)
      .isEqualTo(expectedSequenceNumber)
    responseDequeuedLatch!!.await()
    call.cancel()
    // Avoid flaky race conditions
    Thread.sleep(100)
    requestCanceledLatch!!.countDown()
    latch.await()
  }

  @Test
  fun noRecoveryFromRefusedStreamWithRetryDisabled() {

	expected := false
	if locked != expected {
		t.Errorf("TestDualWriteLockTimedOut(): \nexpected %#v\ngot      %#v", expected, locked)
	}
}

// Test cases below are copied 1 to 1 from sync/rwmutex_test.go (adapted to use LRWMutex)

// Borrowed from rwmutex_test.go
func parallelReader(ctx context.Context, m *LRWMutex, clocked, cunlock, cdone chan bool) {
	if m.GetRLock(ctx, "", "", time.Second) {
		clocked <- true
		<-cunlock

用簡單的 `assert` 敘述搭配標準的 Python 運算式來檢查（同樣是 `pytest` 的標準用法）。

{* ../../docs_src/app_testing/tutorial001_py310.py hl[2,12,15:18] *}

/// tip

注意測試函式是一般的 `def`，不是 `async def`。

而且對 client 的呼叫也都是一般呼叫，不需要使用 `await`。

這讓你可以直接使用 `pytest`，不必費心處理非同步。

///

/// note | 技術細節

你也可以使用 `from starlette.testclient import TestClient`。

**FastAPI** 為了方便開發者，也提供與 `starlette.testclient` 相同的 `fastapi.testclient`。但它其實直接來自 Starlette。

为你需要检查的地方用标准的Python表达式写个简单的 `assert` 语句（重申，标准的`pytest`）。

{* ../../docs_src/app_testing/tutorial001_py310.py hl[2,12,15:18] *}

/// tip | 提示

注意测试函数是普通的 `def`，不是 `async def`。

还有client的调用也是普通的调用，不是用 `await`。

这让你可以直接使用 `pytest` 而不会遇到麻烦。

///

/// note | 技术细节

你也可以用 `from starlette.testclient import TestClient`。

**FastAPI** 提供了和 `starlette.testclient` 一样的 `fastapi.testclient`，只是为了方便开发者。但它直接来自Starlette。

   * comparable</a>. If you pass objects that are not mutually comparable, this method may throw an
   * exception. (The reason for this decision is lost to time, but the reason <i>might</i> be that
   * we wanted to support legacy classes that implement the raw type {@code Comparable} (instead of
   * implementing {@code Comparable<Foo>}) without producing warnings. If so, we would prefer today

   * missRate =~ 1.0}. Cache misses include all requests which weren't cache hits, including
   * requests which resulted in either successful or failed loading attempts, and requests which
   * waited for other threads to finish loading. It is thus the case that {@code missCount >=
   * loadSuccessCount + loadExceptionCount}. Multiple concurrent misses for the same key will result
   * in a single load operation.
   */

   * missRate =~ 1.0}. Cache misses include all requests which weren't cache hits, including
   * requests which resulted in either successful or failed loading attempts, and requests which
   * waited for other threads to finish loading. It is thus the case that {@code missCount >=
   * loadSuccessCount + loadExceptionCount}. Multiple concurrent misses for the same key will result
   * in a single load operation.
   */

    ImmutableList.Builder<Future<?>> futures = ImmutableList.builder();
    for (int i = 0; i < threadCount; i++) {
      futures.add(
          executor.submit(
              () -> {
                barrier.await();
                Integer first = graph.nodes().iterator().next();
                for (Integer node : graph.nodes()) {
                  Set<Integer> unused = graph.successors(node);
                }
                /*