您的**FastAPI**应用程序也可能由一些文件/模块组成等等。

### **FastAPI** app 文件

假设你有一个像 [更大的应用](bigger-applications.md){.internal-link target=_blank} 中所描述的文件结构:

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

在 `main.py` 文件中你有一个 **FastAPI** app:


```Python
{!../../docs_src/app_testing/main.py!}
```

### 测试文件

然后你会有一个包含测试的文件 `test_main.py` 。app可以像Python包那样存在（一样是目录，但有个 `__init__.py` 文件）：

from docs_src.advanced_middleware.tutorial002 import app


def test_middleware():
    client = TestClient(app, base_url="http://example.com")
    response = client.get("/")
    assert response.status_code == 200, response.text
    client = TestClient(app, base_url="http://subdomain.example.com")
    response = client.get("/")
    assert response.status_code == 200, response.text
    client = TestClient(app, base_url="http://invalidhost")

from fastapi.testclient import TestClient

app = FastAPI()

router = APIRouter()


async def common_parameters(q: str, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/main-depends/")
async def main_depends(commons: dict = Depends(common_parameters)):
    return {"in": "main-depends", "params": commons}

from fastapi.testclient import TestClient

from docs_src.behind_a_proxy.tutorial001 import app

client = TestClient(app, root_path="/api/v1")


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi():
    response = client.get("/openapi.json")
    assert response.status_code == 200

import org.apache.logging.log4j.Logger;
import org.codelibs.fess.app.pager.KuromojiPager;
import org.codelibs.fess.app.service.KuromojiService;
import org.codelibs.fess.app.web.CrudMode;
import org.codelibs.fess.app.web.admin.dict.kuromoji.UploadForm;
import org.codelibs.fess.app.web.api.ApiResult;
import org.codelibs.fess.app.web.api.admin.FessApiAdminAction;
import org.codelibs.fess.dict.kuromoji.KuromojiFile;

import org.codelibs.fess.app.web.admin.dashboard.AdminDashboardAction;
import org.codelibs.fess.app.web.admin.dataconfig.AdminDataconfigAction;
import org.codelibs.fess.app.web.admin.design.AdminDesignAction;
import org.codelibs.fess.app.web.admin.dict.AdminDictAction;
import org.codelibs.fess.app.web.admin.duplicatehost.AdminDuplicatehostAction;
import org.codelibs.fess.app.web.admin.elevateword.AdminElevatewordAction;

from fastapi.websockets import WebSocketDisconnect

from ...utils import needs_py310


@pytest.fixture(name="app")
def get_app():
    from docs_src.websockets.tutorial002_an_py310 import app

    return app


@needs_py310
def test_main(app: FastAPI):
    client = TestClient(app)
    response = client.get("/")
    assert response.status_code == 200, response.text

```Python
from unicorn import UnicornMiddleware

app = SomeASGIApp()

new_app = UnicornMiddleware(app, some_config="rainbow")
```

✋️ FastAPI (🤙 💃) 🚚 🙅 🌌 ⚫️ 👈 ⚒ 💭 👈 🔗 🛠️ 🍵 💽 ❌ & 🛃 ⚠ 🐕‍🦺 👷 ☑.

👈, 👆 ⚙️ `app.add_middleware()` (🖼 ⚜).

```Python
from fastapi import FastAPI
from unicorn import UnicornMiddleware

app = FastAPI()

app.add_middleware(UnicornMiddleware, some_config="rainbow")
```

from fastapi import FastAPI
from fastapi.openapi.utils import get_openapi

app = FastAPI()


@app.get("/items/")
async def read_items():
    return [{"name": "Foo"}]


def custom_openapi():
    if app.openapi_schema:
        return app.openapi_schema
    openapi_schema = get_openapi(
        title="Custom title",
        version="2.5.0",
        summary="This is a very custom OpenAPI schema",

import pytest
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.dependencies.tutorial008d_an import app

    client = TestClient(app)
    return client


def test_get_no_item(client: TestClient):
    response = client.get("/items/foo")
    assert response.status_code == 404, response.text
    assert response.json() == {"detail": "Item not found, there's only a plumbus here"}