```txt
Hello, World from Flask!
```

并且如果您访问 <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a>，您将会看到由 FastAPI 返回的响应：

```JSON
{
    "message": "Hello World"
}

以下の引数がサポートされています:

* `allow_origins` - オリジン間リクエストを許可するオリジンのリスト。例えば、`['https://example.org', 'https://www.example.org']`。`['*']`を使用して任意のオリジンを許可できます。
* `allow_origin_regex` - オリジン間リクエストを許可するオリジンの正規表現文字列。例えば、`'https://.*\.example\.org'`。
* `allow_methods` - オリジン間リクエストで許可するHTTPメソッドのリスト。デフォルトは `['GET']` です。`['*']`を使用してすべての標準メソッドを許可できます。

from fastapi.testclient import TestClient

from docs_src.response_model.tutorial003_03 import app

client = TestClient(app)


def test_get_portal():
    response = client.get("/teleport", follow_redirects=False)
    assert response.status_code == 307, response.text
    assert response.headers["location"] == "https://www.youtube.com/watch?v=dQw4w9WgXcQ"


def test_openapi_schema():
    response = client.get("/openapi.json")

    # TODO: in theory this would allow declaring types that could be lists of bytes
    # to be read from files and other types, but I'm not even sure it's a good idea
    # to support it as a first class "feature"
    assert is_bytes_sequence_annotation(Union[List[str], List[bytes]])


def test_is_uploadfile_sequence_annotation():
    # For coverage
    # TODO: in theory this would allow declaring types that could be lists of UploadFile

You can see the available versions (e.g. to check what is the current latest) in the [Release Notes](../release-notes.md){.internal-link target=_blank}.

## About versions

Following the Semantic Versioning conventions, any version below `1.0.0` could potentially add breaking changes.

FastAPI also follows the convention that any "PATCH" version change is for bug fixes and non-breaking changes.

!!! tip

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def root():

import uvicorn
from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def root():
    a = "a"
    b = "b" + a
    return {"hello world": b}


if __name__ == "__main__":

    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Here's your interdimensional portal."}


def test_get_redirect():
    response = client.get("/portal", params={"teleport": True}, follow_redirects=False)
    assert response.status_code == 307, response.text
    assert response.headers["location"] == "https://www.youtube.com/watch?v=dQw4w9WgXcQ"


def test_openapi_schema():

    prefix="/admin",
    tags=["admin"],
    dependencies=[Depends(get_token_header)],
    responses={418: {"description": "I'm a teapot"}},
)


@app.get("/")
async def root():

## Read the Tutorial first

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.