如何使用 FastAPI 客户端在单元测试中修补第 3 方库

Question

我有一个用于 FastAPI 的

app/main.py

，它可以：

import qdrant_client as QdrantClient
... 

qdrant_client = QdrantClient(url=...)
qdrant_client.create_collection(...)
...

app = FastAPI()
...

@app.get("/my_endpoint")
def handle_my_endpoint(query: str):
  ...
  qdrant_client.query_points(...)

我想为

/my_endpoint

写一个单元。

所以我在单元测试文件中有：

from fastapi.testclient import TestClient
from app.main import app

class Test(unittest.TestCase):

    @patch('app.main.QdrantClient', qdrant_client=MagicMock())
    def test_my_endpoint(self, qdrant_client): 
        qdrant_client.create_collection.return_value = None
        with TestClient(app) as client:
            resp = client.get("/my_endpoint", params={...})
            ...

但它不起作用，它坚持实际使用真正的客户端来尝试真正调用 Qdrant 服务器，但失败了......我缺少什么来正确设置

patch

？

Answer 1

重构您的代码以获取

qdrant_client

作为依赖项：

import qdrant_client as QdrantClient
... 

qdrant_client = QdrantClient(url=...)
qdrant_client.create_collection(...)
...

app = FastAPI()
...

async def get_qdrant_client():
  return qdrant_client

@app.get("/my_endpoint")
def handle_my_endpoint(query: str, qdrant_client: Annotated[QdrantClient, Depends(get_qdrant_client)]):
  ...
  qdrant_client.query_points(...)

然后，使用标准 FastAPI 机制进行覆盖：

from fastapi.testclient import TestClient
from app.main import app, get_qdrant_client


@pytest.fixture(name="qdrant_client")
def get_qdrant_client_fixture():
    return MagicMock()

@pytest.fixture(name="test_client")
def get_test_client_fixture(qdrant_client):
    async def get_qdrant_client_mock():
        return qdrant_client

    app.dependency_overrides[get_qdrant_client] = get_qdrant_client_mock

    with TestClient(app) as client:
        yield client

    app.dependency_overrides.clear()



class Test(unittest.TestCase):

    def test_my_endpoint(self, test_client: TestClient, qdrant_client): 
        qdrant_client.create_collection.return_value = None
        resp = client.get("/my_endpoint", params={...})
        ...