`TestClient` 在内部通过一些“魔法”操作，使得您可以在普通的 `def` 测试函数中调用异步的 FastAPI 应用程序，并使用标准的 pytest。但当我们在异步函数中使用它时，这种“魔法”就不再生效了。由于测试以异步方式运行，我们无法在测试函数中继续使用 `TestClient`。

`TestClient` 是基于 [HTTPX](https://www.python-httpx.org) 的。幸运的是，我们可以直接使用它来测试 API。

## 示例 { #example }

举个简单的例子，让我们来看一个与[更大的应用](../tutorial/bigger-applications.md)和[测试](../tutorial/testing.md)中描述的类似文件结构：

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

文件 `main.py` 将包含:

In some cases, it's even possible to have both Pydantic v1 and v2 models in the same **path operation** in your FastAPI app:

{* ../../docs_src/pydantic_v1_in_v2/tutorial003_an_py310.py hl[2:3,6,12,21:22] *}

In this example above, the input model is a Pydantic v1 model, and the output model (defined in `response_model=ItemV2`) is a Pydantic v2 model.

### Pydantic v1 parameters { #pydantic-v1-parameters }

   *
   * <p><b>Warning:</b> contrary to the typical assumptions about predicates (as documented at
   * {@link Predicate#apply}), the returned predicate may not be <i>consistent with equals</i>. For
   * example, {@code instanceOf(ArrayList.class)} will yield different results for the two equal
   * instances {@code Lists.newArrayList(1)} and {@code Arrays.asList(1)}.
   *

    assertThat(cacheControl.noTransform).isTrue()
    assertThat(cacheControl.toString()).isEqualTo(header)
  }

  @Test
  @Throws(Exception::class)
  fun parseIgnoreCacheControlExtensions() {
    // Example from http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.6
    val header = "private, community=\"UCI\""
    val cacheControl =
      parse(
        Headers
          .Builder()

 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedSet} forward <i>indiscriminately</i> to
 * the methods of the delegate. For example, overriding {@link #add} alone <i>will not</i> change
 * the behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should

 * (such as an XML document). Typically (but not always), the inverse process of "unescaping" the
 * text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code
 * "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} from being confused with an XML tag. When the

{* ../../docs_src/app_testing/app_a_py310/test_main.py hl[3] *}

...ve test kodunu da öncekiyle aynı şekilde yazabilirsiniz.

## Test Etme: Genişletilmiş Örnek { #testing-extended-example }

Şimdi bu örneği genişletelim ve farklı parçaların nasıl test edildiğini görmek için daha fazla detay ekleyelim.

### Genişletilmiş **FastAPI** Uygulama Dosyası { #extended-fastapi-app-file }

## `TrustedHostMiddleware` { #trustedhostmiddleware }

强制所有传入请求都必须正确设置 `Host` 请求头，以防 HTTP 主机头攻击。

{* ../../docs_src/advanced_middleware/tutorial002_py310.py hl[2,6:8] *}

支持以下参数：

* `allowed_hosts` - 允许的域名（主机名）列表。`*.example.com` 等通配符域名可以匹配子域名。若要允许任意主机名，可使用 `allowed_hosts=["*"]` 或省略此中间件。
* `www_redirect` - 若设置为 `True`，对允许主机的非 www 版本的请求将被重定向到其 www 版本。默认为 `True`。

如果传入的请求没有通过验证，则发送 `400` 响应。

## `GZipMiddleware` { #gzipmiddleware }

// to compare such streams of bytes that may be split up, because:
//
// Given the function:
//
//	f := func(r io.Reader) string {
//	          b, _ := io.ReadAll(r)
//	          return string(b)
//	}
//
// for example, the following is true:
//
// f(NewDummyDataGen(100, 0)) == f(NewDummyDataGen(50, 0)) + f(NewDummyDataGen(50, 50))
func NewDummyDataGen(totalLength, skipOffset int64) io.ReadSeeker {
	if totalLength < 0 {

 *   <li>Conversion of individual Hankaku Kana characters to Zenkaku Kana characters.</li>
 *   <li>Handling of voiced (ﾞ) and semi-voiced (ﾟ) sound marks to produce the correct Zenkaku Kana characters.</li>
 * </ul>
 *
 * <p>Example usage:</p>
 * <pre>
 * {@code
 * HankakuKanaToZenkakuKana normalizer = new HankakuKanaToZenkakuKana();
 * String normalized = normalizer.normalize("ｶﾞｷﾞｸﾞｹﾞｺﾞ", "field");
 * System.out.println(normalized); // Outputs: ガギグゲゴ