如何为涉及使用Annotated和Depends的Pydantic模型的FastAPI路由编写pytest测试？

Question

我正在尝试使用pytest来测试一个用Python和FastApi创建的简单API。遇到了两个问题：

主要问题：如果函数的输入参数使用了Annotated和Depends，我就无法用pytest运行测试。这个路由返回了一个422 不可处理的实体状态码。
次要问题：在创建测试客户端时，我总是收到一个弃用警告：

> DeprecationWarning: The 'app' shortcut is now deprecated. Use the explicit style 'transport=ASGITransport(app=...)' instead.

请告诉我如何解决这两个问题。我读过关于依赖覆盖的内容，但我不确定这是否是必须的，或者我该如何通过改变输入来为我的应用创建多个测试案例（例如：测试不同的人，以便我的API能为每个人返回不同的输出）。

为了重现这个错误，我创建了一个简单的API，使用的是Python 3.10.13。这个API有两个POST方法的路由，其中一个直接将输入参数声明为Person类的Pydantic模型（我可以测试这个路由，但会有一个弃用警告），而另一个则使用Annotated[Person, Depends()]（我不知道如何测试这个路由，测试失败）：

这是我简单API的main.py文件：

# simple_api/main.py
from fastapi import FastAPI, Depends
from pydantic import BaseModel, Field
from typing import Annotated

# Define a simple Pydantic v2 model to validate the post request
class Person(BaseModel):
    name: str
    age: int = Field(..., ge=18, le = 130)

# Load app
app = FastAPI()

# I can test this route:
@app.post("/post_no_dependency")
def post_example_no_dependency(person: Person):
    return {
        "message": f"Hello {person.name}, your age is {person.age}",
        "method": "no dependency"
        }

# But I am not sure how to test this route:
@app.post("/post_with_dependency")
def post_example_with_dependency(
    person: Annotated[Person, Depends()]
    ):
    return {
        "message": f"Hello {person.name}, your age is {person.age}",
        "method":"with dependency"
        }

这是我简单API的测试文件：

# /simple_api/test_simple_api.py
import pytest
from httpx import AsyncClient

from main import app

@pytest.fixture
async def async_client():
  """Fixture to create a FastAPI test client."""
  async with AsyncClient(app=app, base_url="http://test") as async_test_client:
      yield async_test_client

# This test works
@pytest.mark.anyio
async def test_post_example_no_dependency(async_client: AsyncClient):
    data = {"name": "john doe",
            "age": 32}
    response = await async_client.post("/post_no_dependency",
                                       json = data)
    assert response.status_code == 200
    assert response.json()["method"] == "no dependency"

# This test fails because the status code is 422, not 200.
@pytest.mark.anyio
async def test_post_example_with_dependency(async_client: AsyncClient):
    data = {"name": "john doe",
            "age": 32}
    response = await async_client.post("/post_with_dependency",
                                       json = data)
    assert response.status_code == 200
    assert response.json()["method"] == "with dependency"

这是我在bash终端运行pytest时发生的情况（我正在使用github codespace）：

(simple_venv) @mikeliux ➜ /workspaces/simple_api $ pytest test_simple_api.py
==================================================================== test session starts ====================================================================
platform linux -- Python 3.10.13, pytest-8.1.1, pluggy-1.4.0
rootdir: /workspaces/simple_api
plugins: anyio-4.3.0
collected 4 items                                                                                                                                           

test_simple_api.py .F.F                                                                                                                               [100%]

========================================================================= FAILURES ==========================================================================
________________________________________________________ test_post_example_with_dependency[asyncio] _________________________________________________________

async_client = <httpx.AsyncClient object at 0x7f0e0cd893f0>

    @pytest.mark.anyio
    async def test_post_example_with_dependency(async_client: AsyncClient):
        data = {"name": "john doe",
                "age": 32}
        response = await async_client.post("/post_with_dependency",
                                           json = data)
>       assert response.status_code == 200
E       assert 422 == 200
E        +  where 422 = <Response [422 Unprocessable Entity]>.status_code

test_simple_api.py:30: AssertionError
__________________________________________________________ test_post_example_with_dependency[trio] __________________________________________________________

async_client = <httpx.AsyncClient object at 0x7f0e0c436770>

    @pytest.mark.anyio
    async def test_post_example_with_dependency(async_client: AsyncClient):
        data = {"name": "john doe",
                "age": 32}
        response = await async_client.post("/post_with_dependency",
                                           json = data)
>       assert response.status_code == 200
E       assert 422 == 200
E        +  where 422 = <Response [422 Unprocessable Entity]>.status_code

test_simple_api.py:30: AssertionError
===================================================================== warnings summary ======================================================================
test_simple_api.py::test_post_example_no_dependency[asyncio]
test_simple_api.py::test_post_example_with_dependency[asyncio]
test_simple_api.py::test_post_example_no_dependency[trio]
test_simple_api.py::test_post_example_with_dependency[trio]
  /workspaces/simple_api/simple_venv/lib/python3.10/site-packages/httpx/_client.py:1426: DeprecationWarning: The 'app' shortcut is now deprecated. Use the explicit style 'transport=ASGITransport(app=...)' instead.
    warnings.warn(message, DeprecationWarning)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
================================================================== short test summary info ==================================================================
FAILED test_simple_api.py::test_post_example_with_dependency[asyncio] - assert 422 == 200
FAILED test_simple_api.py::test_post_example_with_dependency[trio] - assert 422 == 200
========================================================== 2 failed, 2 passed, 4 warnings in 0.77s ==========================================================

另外，你可以在这里查看已安装的包：

(simple_venv) @mikeliux ➜ /workspaces/simple_api $ pip freeze
annotated-types==0.6.0
anyio==4.3.0
attrs==23.2.0
certifi==2024.2.2
click==8.1.7
dnspython==2.6.1
email_validator==2.1.1
exceptiongroup==1.2.0
fastapi==0.110.0
h11==0.14.0
httpcore==1.0.5
httptools==0.6.1
httpx==0.27.0
idna==3.6
iniconfig==2.0.0
itsdangerous==2.1.2
Jinja2==3.1.3
MarkupSafe==2.1.5
orjson==3.10.0
outcome==1.3.0.post0
packaging==24.0
pluggy==1.4.0
pydantic==2.6.4
pydantic-extra-types==2.6.0
pydantic-settings==2.2.1
pydantic_core==2.16.3
pytest==8.1.1
python-dotenv==1.0.1
python-multipart==0.0.9
PyYAML==6.0.1
sniffio==1.3.1
sortedcontainers==2.4.0
starlette==0.36.3
tomli==2.0.1
trio==0.25.0
typing_extensions==4.10.0
ujson==5.9.0
uvicorn==0.29.0
uvloop==0.19.0
watchfiles==0.21.0
websockets==12.0

谢谢你提前的帮助

error handling api testing fastapi pytest pydantic dependency injection test client http status codes

如何为涉及使用Annotated和Depends的Pydantic模型的FastAPI路由编写pytest测试？

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