<script>
        var ws = null;
            function connect(event) {
                var itemId = document.getElementById("itemId")
                var token = document.getElementById("token")
                ws = new WebSocket("ws://localhost:8000/items/" + itemId.value + "/ws?token=" + token.value);
                ws.onmessage = function(event) {
                    var messages = document.getElementById('messages')

        <script>
        var ws = null;
            function connect(event) {
                var itemId = document.getElementById("itemId")
                var token = document.getElementById("token")
                ws = new WebSocket("ws://localhost:8000/items/" + itemId.value + "/ws?token=" + token.value);
                ws.onmessage = function(event) {
                    var messages = document.getElementById('messages')

	// This is traditionally the client identifier issued to the application that
	// requested the client grants.
	Audience string `xml:",omitempty"`

	// The temporary security credentials, which include an access key ID, a secret
	// access key, and a security (or session) token.
	//
	// Note: The size of the security token that STS APIs return is not fixed. We

        // Security Buffer Length
        assertEquals(token.length, SMBUtil.readInt2(buffer, bodyOffset + 14));

        // Previous Session ID
        assertEquals(previousSessionId, SMBUtil.readInt8(buffer, bodyOffset + 16));

        // Token content
        byte[] actualToken = new byte[token.length];
        System.arraycopy(buffer, securityBufferOffset, actualToken, 0, token.length);
        assertArrayEquals(token, actualToken);

Se não houver um header `Authorization`, ou se o valor não tiver um token `Bearer `, ele responderá diretamente com um erro de status 401 (`UNAUTHORIZED`).

Você nem precisa verificar se o token existe para retornar um erro. Você pode ter certeza de que, se sua função for executada, ela terá uma `str` nesse token.

Si no ve un header `Authorization`, o el valor no tiene un token `Bearer `, responderá directamente con un error de código de estado 401 (`UNAUTHORIZED`).

Ni siquiera tienes que verificar si el token existe para devolver un error. Puedes estar seguro de que si tu función se ejecuta, tendrá un `str` en ese token.

Puedes probarlo ya en los docs interactivos:

def test_read_nonexistent_item():
    response = client.get("/items/baz", headers={"X-Token": "coneofsilence"})
    assert response.status_code == 404
    assert response.json() == {"detail": "Item not found"}


def test_create_item():
    response = client.post(
        "/items/",
        headers={"X-Token": "coneofsilence"},

@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"X-Token values": None}),
        ("/items", {"x-token": "foo"}, 200, {"X-Token values": ["foo"]}),
        (
            "/items",
            [("x-token", "foo"), ("x-token", "bar")],
            200,
            {"X-Token values": ["foo", "bar"]},
        ),
    ],
)

        }, "A PACDecodingException should be thrown for a malformed token.");

        assertEquals("Malformed kerberos ticket", exception.getMessage(), "The exception message should indicate a malformed ticket.");
    }

    /**
     * Test constructor with an empty token.
     * Empty token causes readObject() to return null, which leads to NullPointerException.
     */
    @Test

app = FastAPI()

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="/token",
    description="OAuth2PasswordBearer security scheme",
    auto_error=False,
)


@app.get("/items/")
async def read_items(token: Optional[str] = Security(oauth2_scheme)):
    if token is None:
        return {"msg": "Create an account first"}
    return {"token": token}


client = TestClient(app)


def test_no_token():