from fastapi import FastAPI, Path, Query, status
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/{repeated_alias}")
def get_parameters_with_repeated_aliases(
    path: str = Path(..., alias="repeated_alias"),
    query: str = Query(..., alias="repeated_alias"),
):
    return {"path": path, "query": query}


client = TestClient(app)


def test_get_parameters():

class FooBaseModel(BaseModel):
    model_config = ConfigDict(extra="forbid")


class Foo(FooBaseModel):
    pass


app = FastAPI()


@app.post("/")
async def post(
    foo: Union[Foo, None] = None,
):
    return foo


client = TestClient(app)


def test_call_invalid():
    response = client.post("/", json={"foo": {"bar": "baz"}})
    assert response.status_code == 422

import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient


@pytest.fixture(name="app", scope="module")
def get_app():
    with pytest.warns(DeprecationWarning):
        from docs_src.events.tutorial002_py39 import app
    yield app


def test_events(app: FastAPI):
    with TestClient(app) as client:
        response = client.get("/items/")
        assert response.status_code == 200, response.text

from fastapi import APIRouter, FastAPI, Query
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/default")
async def default(foo: Annotated[str, Query()] = "foo"):
    return {"foo": foo}


@app.get("/required")
async def required(foo: Annotated[str, Query(min_length=1)]):
    return {"foo": foo}


@app.get("/multiple")
async def multiple(foo: Annotated[str, object(), Query(min_length=1)]):

from fastapi.testclient import TestClient

from docs_src.handling_errors.tutorial001_py39 import app

client = TestClient(app)


def test_get_item():
    response = client.get("/items/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"item": "The Foo Wrestlers"}


def test_get_item_not_found():
    response = client.get("/items/bar")
    assert response.status_code == 404, response.text

from fastapi.testclient import TestClient

from docs_src.generate_clients.tutorial003_py39 import app

client = TestClient(app)


def test_post_items():
    response = client.post("/items/", json={"name": "Foo", "price": 5})
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Item received"}


def test_post_users():
    response = client.post(

En el camino de la request, el middleware más externo se ejecuta primero.

En el camino de la response, se ejecuta al final.

Por ejemplo:

```Python
app.add_middleware(MiddlewareA)

from fastapi.testclient import TestClient

app = FastAPI()

T = TypeVar("T")

Dep = Annotated[T, Depends()]


class A:
    pass


class B:
    pass


@app.get("/a")
async def a(dep: Dep[A]):
    return {"cls": dep.__class__.__name__}


@app.get("/b")
async def b(dep: Dep[B]):
    return {"cls": dep.__class__.__name__}


client = TestClient(app)

from fastapi import FastAPI

from . import a, b

app = FastAPI()

app.include_router(a.router, prefix="/a")

常见实例是调用外部第三方身份验证应用。

向第三方应用发送令牌，然后返回经验证的用户。

但第三方服务商处理每次请求都可能会收费，并且耗时通常也比调用写死的模拟测试用户更长。

一般只要测试一次外部验证应用就够了，不必每次测试都去调用。

此时，最好覆盖调用外部验证应用的依赖项，使用返回模拟测试用户的自定义依赖项就可以了。

### 使用 `app.dependency_overrides` 属性

对于这些用例，**FastAPI** 应用支持 `app.dependency_overrides` 属性，该属性就是**字典**。

要在测试时覆盖原有依赖项，这个字典的键应当是原依赖项（函数），值是覆盖依赖项（另一个函数）。

这样一来，**FastAPI** 就会调用覆盖依赖项，不再调用原依赖项。