{* ../../docs_src/sub_applications/tutorial001_py39.py hl[3, 6:8] *}

### Unteranwendung { #sub-application }

Erstellen Sie dann Ihre Unteranwendung und deren *Pfadoperationen*.

Diese Unteranwendung ist nur eine weitere Standard-FastAPI-Anwendung, aber diese wird „gemountet“:

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 14:16] *}

from fastapi.testclient import TestClient

from docs_src.metadata.tutorial002_py39 import app

client = TestClient(app)


def test_items():
    response = client.get("/items/")
    assert response.status_code == 200, response.text
    assert response.json() == [{"name": "Foo"}]


def test_get_openapi_json_default_url():
    response = client.get("/openapi.json")
    assert response.status_code == 404, response.text

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[3, 6:8] *}

### Sub-application { #sub-application }

Then, create your sub-application, and its *path operations*.

This sub-application is just another standard FastAPI application, but this is the one that will be "mounted":

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 14:16] *}

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Добавление фоновой задачи { #add-the-background-task }

Внутри вашей функции‑обработчика пути передайте функцию задачи объекту фоновых задач методом `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[14] *}

`.add_task()` принимает следующие аргументы:

# Probando WebSockets { #testing-websockets }

Puedes usar el mismo `TestClient` para probar WebSockets.

Para esto, usas el `TestClient` en un statement `with`, conectándote al WebSocket:

{* ../../docs_src/app_testing/tutorial002_py39.py hl[27:31] *}

/// note | Nota

from fastapi.testclient import TestClient

from docs_src.response_headers.tutorial002_py39 import app

client = TestClient(app)


def test_path_operation():
    response = client.get("/headers-and-object/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Hello World"}

import pytest
from dirty_equals import IsOneOf
from fastapi.testclient import TestClient

from tests.utils import needs_py310


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial002_py39"),
        pytest.param("tutorial002_py310", marks=needs_py310),
        pytest.param("tutorial002_an_py39"),
        pytest.param("tutorial002_an_py310", marks=needs_py310),
    ],
)

from docs_src.python_types.tutorial004_py39 import get_name_with_age


def test_get_name_with_age_pass_int():

Вы можете использовать тот же `TestClient` для тестирования WebSocket.

Для этого используйте `TestClient` с менеджером контекста `with`, подключаясь к WebSocket:

{* ../../docs_src/app_testing/tutorial002_py39.py hl[27:31] *}

/// note | Примечание

import importlib

import pytest
from fastapi.testclient import TestClient


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial002_py39"),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.response_directly.{request.param}")

    client = TestClient(mod.app)
    return client


def test_path_operation(client: TestClient):