* Sie nimmt jeden **Request** entgegen, der an Ihre Anwendung gesendet wird.
* Sie kann dann etwas mit diesem **Request** tun oder beliebigen Code ausführen.
* Dann gibt sie den **Request** zur Verarbeitung durch den Rest der Anwendung weiter (durch eine bestimmte *Pfadoperation*).

client = TestClient(app)


def test_filter_top_level_model():
    response = client.post(
        "/users", json={"email": "******@****.***", "password": "secret"}
    )
    assert response.json() == {"email": "******@****.***"}


def test_filter_second_level_model():
    response = client.get("/pets/1")
    assert response.json() == {
        "name": "Nibbler",
        "owner": {"email": "******@****.***"},

    response = client.get("/users/me", headers={"Authorization": "Basic notreally"})
    assert response.status_code == 403, response.text
    assert response.json() == {"detail": "Invalid authentication credentials"}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",

client = TestClient(app)


def test_get_item():
    response = client.get("/items/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"item": "The Foo Wrestlers"}


def test_get_item_not_found():
    response = client.get("/items/bar")
    assert response.status_code == 404, response.text
    assert response.headers.get("x-error") is None
    assert response.json() == {"detail": "Item not found"}

def test_multi_query_values():
    url = "/items/?q=foo&q=bar"
    response = client.get(url)
    assert response.status_code == 200, response.text
    assert response.json() == {"q": ["foo", "bar"]}


def test_query_no_values():
    url = "/items/"
    response = client.get(url)
    assert response.status_code == 200, response.text
    assert response.json() == {"q": []}


def test_openapi_schema():

@needs_py310
def test_hidden_query(client: TestClient):
    response = client.get("/items?hidden_query=somevalue")
    assert response.status_code == 200, response.text
    assert response.json() == {"hidden_query": "somevalue"}


@needs_py310
def test_no_hidden_query(client: TestClient):
    response = client.get("/items")
    assert response.status_code == 200, response.text
    assert response.json() == {"hidden_query": "Not found"}

        .url("https://server/robots.txt")
        .build()
    val response =
      Response.Builder()
        .request(request)
        .code(401)
        .header("WWW-Authenticate", "Basic realm=\"User Visible Realm\"")
        .protocol(HTTP_2)
        .message("Unauthorized")
        .build()
    val authRequest = authenticator.authenticate(route, response)

    assertEquals(

      val request = SimpleHttpRequests.get("https://google.com/robots.txt")
      val response = client.execute(request, LoggingCallback).get()

      println("Protocol ${response.version}")
      println("Response ${response.code}")
      println("${response.body.bodyText.substring(0, 20)}...")

      Assert.assertEquals(ProtocolVersion("HTTP", 2, 0), response.version)
    }
  }
}

            engineObj.activeShards = response.getActiveShards();
            engineObj.activeShardsPercent = response.getActiveShardsPercent();
            engineObj.relocatingShards = response.getRelocatingShards();
            engineObj.initializingShards = response.getInitializingShards();
            engineObj.unassignedShards = response.getUnassignedShards();
            engineObj.delayedUnassignedShards = response.getDelayedUnassignedShards();

```

////

Notice that the *path operations* define the models they use for request payload and response payload, using the models `Item` and `ResponseMessage`.

### API Docs

If you go to the API docs, you will see that it has the **schemas** for the data to be sent in requests and received in responses:

<img src="/img/tutorial/generate-clients/image01.png">