// ## Arrange ##
        CurlRequest req = new OpenOverrideCurlRequest(Curl.Method.HEAD, "http://dummy", u -> new HeadMockHttpURLConnection(u, 404));

        // ## Act ##
        try (CurlResponse response = req.execute()) {
            // ## Assert ##
            assertEquals(404, response.getHttpStatusCode());
            String content = response.getContentAsString();
            assertEquals("", content);
        }
    }

///

## Response Status Code { #response-status-code }

You can define the (HTTP) `status_code` to be used in the response of your *path operation*.

You can pass directly the `int` code, like `404`.

But if you don't remember what each number code is for, you can use the shortcut constants in `status`:

{* ../../docs_src/path_operation_configuration/tutorial001_py310.py hl[1,15] *}

* **`400 - 499`** are for "Client error" responses. These are the second type you would probably use the most.
    * An example is `404`, for a "Not Found" response.
    * For generic errors from the client, you can just use `400`.

```console
$ OPENAPI_URL= uvicorn main:app

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

之後若你造訪 `/openapi.json`、`/docs` 或 `/redoc`，會看到如下的 `404 Not Found` 錯誤：

```JSON
{
    "detail": "Not Found"
}

     * The HTTP status code for Forbidden.
     */
    public static final int FORBIDDEN_STATUS_CODE = 403;

    /**
     * The HTTP status code for Not Found.
     */
    public static final int NOT_FOUND_STATUS_CODE = 404;

    /**
     * The HTTP status code for Server Error.
     */
    public static final int SERVER_ERROR_STATUS_CODE = 500;

    /**
     * A constant for no transformer.
     */

    Request request = new Request.Builder()
            .url(url)
            .build();
    try (Response response = client.newCall(request).execute()) {
      assertTrue(response.code() == 200 || response.code() == 404);
      assertEquals(Protocol.HTTP_2, response.protocol());
    }
  }

                .body("{\\\"info\\\":{\\\"name\":\"Lucas Albuquerque\",\"age\":\"21\",\"gender\":\"male\"}}")
                .build();
        }
        return new MockResponse.Builder()
            .code(404)
            .build();
    }
};
server.setDispatcher(dispatcher);
```

### Kotlin
```kotlin
val dispatcher = object : Dispatcher() {

    }
  }

  private fun send404(
    stream: Http2Stream,
    path: String,
  ) {
    val responseHeaders =
      listOf(
        Header(":status", "404"),
        Header(":version", "HTTP/1.1"),
        Header("content-type", "text/plain"),
      )
    stream.writeHeaders(
      responseHeaders = responseHeaders,
      outFinished = false,

$ OPENAPI_URL= uvicorn main:app

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

すると、以下のように `/openapi.json`, `/docs`, `/redoc` のどのURLにアクセスしても、 `404 Not Found` エラーが返ってくるようになります。

```JSON
{
    "detail": "Not Found"
}

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

Then if you go to the URLs at `/openapi.json`, `/docs`, or `/redoc` you will just get a `404 Not Found` error like:

```JSON
{
    "detail": "Not Found"
}