您已经了解了如何使用 `TestClient` 测试 **FastAPI** 应用程序。但是到目前为止，您只了解了如何编写同步测试，而没有使用 `async` 异步函数。

在测试中能够使用异步函数可能会很有用，比如当您需要异步查询数据库的时候。想象一下，您想要测试向 FastAPI 应用程序发送请求，然后验证您的后端是否成功在数据库中写入了正确的数据，与此同时您使用了异步的数据库的库。

让我们看看如何才能实现这一点。

## pytest.mark.anyio

如果我们想在测试中调用异步函数，那么我们的测试函数必须是异步的。 AnyIO 为此提供了一个简洁的插件，它允许我们指定一些测试函数要异步调用。

## HTTPX

即使您的 **FastAPI** 应用程序使用普通的 `def` 函数而不是 `async def` ，它本质上仍是一个 `async` 异步应用程序。

        @Test
        @DisplayName("createCancel should return Smb2CancelRequest with same mid and asyncId")
        void testCreateCancel() {
            long mid = 123L;
            long asyncId = 456L;
            testRequest.setMid(mid);
            testRequest.setAsyncId(asyncId);

            CommonServerMessageBlockRequest cancelRequest = testRequest.createCancel();

        assertEquals(asyncId, request.getAsyncId());
        assertTrue((request.getFlags() & SMB2_FLAGS_ASYNC_COMMAND) != 0, "Async flag should be set when asyncId is non-zero");
    }

    @Test
    @DisplayName("Test constructor with zero asyncId does not set async flag")
    void testConstructorWithZeroAsyncId() {
        // Given
        long mid = 12345L;
        long asyncId = 0L;

        // When

     *
     * @return the asyncId
     */
    public final long getAsyncId() {
        return this.asyncId;
    }

    /**
     * Sets the asynchronous identifier for this message.
     *
     * @param asyncId
     *            the asyncId to set
     */
    public final void setAsyncId(final long asyncId) {
        this.asyncId = asyncId;
    }

    /**

     *            The message ID of the request to cancel
     * @param asyncId
     *            The async ID for asynchronous operations (0 for synchronous)
     */
    public Smb2CancelRequest(final Configuration config, final long mid, final long asyncId) {
        super(config, SMB2_CANCEL);
        setMid(mid);
        setAsyncId(asyncId);
        if (asyncId != 0) {
            addFlags(SMB2_FLAGS_ASYNC_COMMAND);
        }
    }

* Fix typos in Async docs. PR [#1423](https://github.com/tiangolo/fastapi/pull/1423).

## 0.54.2

* Add translation to Spanish for [Concurrency and async / await - Concurrencia y async / await](https://fastapi.tiangolo.com/es/async/). PR [#1290](https://github.com/tiangolo/fastapi/pull/1290) by [@alvaropernas](https://github.com/alvaropernas).

@app.get("/callable-gen-dependency")
async def get_callable_gen_dependency(value: str = Depends(callable_gen_dependency)):
    return value


@app.get("/async-callable-dependency")
async def get_async_callable_dependency(
    value: str = Depends(async_callable_dependency),
):
    return value


@app.get("/async-callable-gen-dependency")
async def get_async_callable_gen_dependency(
    value: str = Depends(async_callable_gen_dependency),
):

@app.get("/async/large-dict-no-response-model")
async def async_large_dict_no_response_model():
    return LARGE_PAYLOAD


@app.get("/async/large-dict-with-response-model", response_model=LargeOut)
async def async_large_dict_with_response_model():
    return LARGE_PAYLOAD


@app.get("/async/large-model-no-response-model")
async def async_large_model_no_response_model():

    return value


@app.get("/partial-async-callable-dependency")
async def get_partial_async_callable_dependency(
    value: Annotated[
        str,
        Depends(
            partial(async_callable_dependency, "partial-async-callable-dependency")
        ),
    ],
) -> str:
    return value


@app.get("/partial-async-callable-gen-dependency")
async def get_partial_async_callable_gen_dependency(

    async.setFuture(inner);
    async.cancel(false);
    assertTrue(inner.isCancelled());
    assertFalse(inner.wasInterrupted());
    assertThrows(CancellationException.class, () -> inner.get());
  }

  public void testCancel_beforeSet() throws Exception {
    SettableFuture<Object> async = SettableFuture.create();
    async.cancel(true);
    assertFalse(async.set(42));
  }