Чтобы работать с асинхронным FastAPI приложением в ваших обычных тестовых функциях `def`, используя стандартный pytest, `TestClient` внутри себя делает некоторую магию. Но эта магия перестает работать, когда мы используем его внутри асинхронных функций. Запуская наши тесты асинхронно, мы больше не можем использовать `TestClient` внутри наших тестовых функций.

import importlib

import pytest
from fastapi.testclient import TestClient


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial007_py39"),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(
        f"docs_src.path_operation_advanced_configuration.{request.param}"
    )

    client = TestClient(mod.app)
    return client

from fastapi import Cookie, FastAPI, Header, Query
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Model(BaseModel):
    param: str

    model_config = {"extra": "allow"}


@app.get("/query")
async def query_model_with_extra(data: Model = Query()):
    return data


@app.get("/header")
async def header_model_with_extra(data: Model = Header()):
    return data

    client = TestClient(mod.app)
    return client


@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"User-Agent": "testclient"}),
        ("/items", {"X-Header": "notvalid"}, 200, {"User-Agent": "testclient"}),
        ("/items", {"User-Agent": "FastAPI test"}, 200, {"User-Agent": "FastAPI test"}),
    ],

import io
from pathlib import Path

import pytest
from fastapi import FastAPI, UploadFile
from fastapi.datastructures import Default
from fastapi.testclient import TestClient


def test_upload_file_invalid_pydantic_v2():
    with pytest.raises(ValueError):
        UploadFile._validate("not a Starlette UploadFile", {})


def test_default_placeholder_equals():
    placeholder_1 = Default("a")
    placeholder_2 = Default("a")

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Product(BaseModel):
    name: str
    description: str = None  # type: ignore
    price: float


@app.get("/product")
async def create_item(product: Product):
    return product


client = TestClient(app)


def test_get_with_body():

from fastapi import Depends, FastAPI, Header, status
from fastapi.testclient import TestClient

app = FastAPI()


def get_header(*, someheader: str = Header()):
    return someheader


def get_something_else(*, someheader: str = Depends(get_header)):
    return f"{someheader}123"


@app.get("/")
def get_deps(dep1: str = Depends(get_header), dep2: str = Depends(get_something_else)):
    return {"dep1": dep1, "dep2": dep2}

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():

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


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():

from fastapi import FastAPI
from fastapi.responses import JSONResponse
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class JsonApiResponse(JSONResponse):
    media_type = "application/vnd.api+json"


class Error(BaseModel):
    status: str
    title: str


class JsonApiError(BaseModel):
    errors: list[Error]


@app.get(
    "/a",