Ref: https://github.com/Kludex/starlette/pull/3117
    """

    def __init__(self, router: "APIRouter") -> None:
        self._router = router

    async def __aenter__(self) -> None:
        await self._router._startup()

    async def __aexit__(self, *exc_info: object) -> None:
        await self._router._shutdown()

    def __call__(self: _T, app: object) -> _T:
        return self

來看看怎麼做。

## pytest.mark.anyio { #pytest-mark-anyio }

若要在測試中呼叫非同步函式，測試函式本身也必須是非同步的。AnyIO 為此提供了一個好用的外掛，讓我們可以標示某些測試函式以非同步方式執行。

## HTTPX { #httpx }

即使你的 FastAPI 應用使用一般的 `def` 函式而非 `async def`，它在底層仍然是個 `async` 應用。

`TestClient` 在內部做了一些魔法，讓我們能在一般的 `def` 測試函式中，使用標準 pytest 來呼叫非同步的 FastAPI 應用。但當我們在非同步函式中使用它時，這個魔法就不再奏效了。也就是說，當以非同步方式執行測試時，就不能在測試函式內使用 `TestClient`。

`TestClient` 是建立在 [HTTPX](https://www.python-httpx.org) 之上，所幸我們可以直接使用它來測試 API。

app = FastAPI()

security = HTTPBasic(realm="simple", description="HTTPBasic scheme")


@app.get("/users/me")
def read_current_user(credentials: HTTPBasicCredentials = Security(security)):
    return {"username": credentials.username, "password": credentials.password}


client = TestClient(app)


def test_security_http_basic():
    response = client.get("/users/me", auth=("john", "secret"))

    name: str

    @computed_field
    @property
    def computed_field(self) -> str:
        return f"computed {self.name}"


def get_app_client(separate_input_output_schemas: bool = True) -> TestClient:
    app = FastAPI(separate_input_output_schemas=separate_input_output_schemas)

    @app.post("/items/", responses={402: {"model": Item}})
    def create_item(item: Item) -> Item:
        return item

from functools import lru_cache
from typing import Annotated

from fastapi import Depends, FastAPI

from . import config

app = FastAPI()


@lru_cache
def get_settings():
    return config.Settings()


@app.get("/info")
async def info(settings: Annotated[config.Settings, Depends(get_settings)]):
    return {
        "app_name": settings.app_name,
        "admin_email": settings.admin_email,

app = FastAPI()


class FixedContentQueryChecker:
    def __init__(self, fixed_content: str):
        self.fixed_content = fixed_content

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: bool = Depends(checker)):

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

    If you need a refresher about when to use which, check out the section _"In a hurry?"_ in the docs about [`async` and `await`](../async.md#in-a-hurry).

class PartialGitHubEventIssue(BaseModel):
    number: int | None = None


class PartialGitHubEvent(BaseModel):
    pull_request: PartialGitHubEventIssue | None = None


def get_graphql_response(
    *,
    settings: Settings,
    query: str,
    after: str | None = None,
    category_id: str | None = None,
    discussion_number: int | None = None,

app = FastAPI()


@app.post("/form/")
def post_form(username: Annotated[str, Form()]):
    return username


client = TestClient(app)


def test_single_form_field():
    response = client.post("/form/", data={"username": "Rick"})
    assert response.status_code == 200, response.text
    assert response.json() == "Rick"


def test_openapi_schema():
    response = client.get("/openapi.json")

    items: dict[str, int]


@app.post("/foo")
def foo(items: Items):
    return items.items


client = TestClient(app)


def test_additional_properties_post():
    response = client.post("/foo", json={"items": {"foo": 1, "bar": 2}})
    assert response.status_code == 200, response.text
    assert response.json() == {"foo": 1, "bar": 2}


def test_openapi_schema():
    response = client.get("/openapi.json")