response = client.get(
        "/items/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )
    assert response.status_code == 400, response.text
    assert response.json() == {"detail": "X-Key header invalid"}


def test_get_invalid_second_header_users():
    response = client.get(
        "/users/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )

    response = client.get(
        "/items/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )
    assert response.status_code == 400, response.text
    assert response.json() == {"detail": "X-Key header invalid"}


def test_get_invalid_second_header_users():
    response = client.get(
        "/users/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )

        "/items/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )
    assert response.status_code == 400, response.text
    assert response.json() == {"detail": "X-Key header invalid"}


def test_get_valid_headers():
    response = client.get(
        "/items/",
        headers={
            "X-Token": "fake-super-secret-token",
            "X-Key": "fake-super-secret-key",
        },
    )

        "/items/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )
    assert response.status_code == 400, response.text
    assert response.json() == {"detail": "X-Key header invalid"}


def test_get_valid_headers():
    response = client.get(
        "/items/",
        headers={
            "X-Token": "fake-super-secret-token",
            "X-Key": "fake-super-secret-key",
        },
    )

        "/items?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200
    assert response.json() == {
        "plumbus": {"name": "Plumbus"},
        "gun": {"name": "Portal Gun"},
    }


def test_items_with_no_token_jessica(client: TestClient):
    response = client.get("/items", headers={"X-Token": "fake-super-secret-token"})
    assert response.status_code == 422

        "/items?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200
    assert response.json() == {
        "plumbus": {"name": "Plumbus"},
        "gun": {"name": "Portal Gun"},
    }


@needs_py39
def test_items_with_no_token_jessica(client: TestClient):
    response = client.get("/items", headers={"X-Token": "fake-super-secret-token"})

## Simple usage

If you look at it, *path operation functions* are declared to be used whenever a *path* and *operation* matches, and then **FastAPI** takes care of calling the function with the correct parameters, extracting the data from the request.

Actually, all (or most) of the web frameworks work in this same way.

You never call those functions directly. They are called by your framework (in this case, **FastAPI**).

        "/items/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )
    assert response.status_code == 400, response.text
    assert response.json() == {"detail": "X-Key header invalid"}


@needs_py39
def test_get_invalid_second_header_users(client: TestClient):
    response = client.get(
        "/users/", headers={"X-Token": "fake-super-secret-token", "X-Key": "invalid"}
    )

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

First, create the main, top-level, **FastAPI** application, and its *path operations*:

You could use these tools and ideas if you are setting up **your own deployment system** while taking care of the other deployment concepts yourself.