Frontend client

HTTP client representing frontend-web calling user-service.

This module is intentionally free of any Pact dependency; it is production code. The Pact dependency only appears in test_consumer_frontend, which exercises this client against a Pact mock server to define the contract between frontend-web (consumer) and user_service (provider).

Notice that the Account dataclass only captures the fields frontend-web cares about (id, username, status). This is a deliberate illustration of how consumer-driven contracts differ from testing an OpenAPI specification: the contract describes what this consumer uses, not everything the provider exposes.

Classes

Account(id: int, username: str, status: str) dataclass

Minimal account model as seen by frontend-web.

This class intentionally reflects only the fields the frontend consumer needs. It may differ from the internal representation in user_service, which stores additional state. This asymmetry is expected and is a key feature of consumer-driven contract testing.

Attributes

id: int instance-attribute

status: str instance-attribute

username: str instance-attribute

FrontendClient(base_url: str)

HTTP client used by frontend-web to call user-service.

This client is the consumer under test in test_consumer_frontend. Keeping it free of Pact dependencies means it can be used as-is in production while the tests handle all contract verification.

PARAMETER	DESCRIPTION
base_url	Base URL of user-service, e.g. http://user-service. Trailing slashes are stripped automatically. TYPE: str

Source code in examples/http/service_consumer_provider/frontend_client.py

def __init__(self, base_url: str) -> None:
    """
    Initialise the frontend client.

    Args:
        base_url:
            Base URL of `user-service`, e.g. `http://user-service`. Trailing
            slashes are stripped automatically.
    """
    self._base_url = base_url.rstrip("/")
    self._session = requests.Session()

Functions

create_account(username: str, password: str) -> Account

Create an account through user-service.

Sends a POST /accounts request and deserialises the response into an Account. Only the id, username, and status fields are read from the response, and any additional fields returned by the provider are ignored.

PARAMETER	DESCRIPTION
username	Desired username for the new account. TYPE: str
password	Password forwarded to user-service, which validates it against auth-service before creating the account. TYPE: str

RETURNS	DESCRIPTION
Account	Account data returned by user-service.

RAISES	DESCRIPTION
HTTPError	If user-service responds with a non-2xx status (e.g., 401 when credentials are rejected).

Source code in examples/http/service_consumer_provider/frontend_client.py

def create_account(self, username: str, password: str) -> Account:
    """
    Create an account through `user-service`.

    Sends a `POST /accounts` request and deserialises the response into an
    [`Account`][examples.http.service_consumer_provider.frontend_client.Account].
    Only the `id`, `username`, and `status` fields are read from the
    response, and any additional fields returned by the provider are
    ignored.

    Args:
        username:
            Desired username for the new account.

        password:
            Password forwarded to `user-service`, which validates it against
            `auth-service` before creating the account.

    Returns:
        Account data returned by `user-service`.

    Raises:
        requests.HTTPError:
            If `user-service` responds with a non-2xx status (e.g., `401`
            when credentials are rejected).
    """
    response = self._session.post(
        f"{self._base_url}/accounts",
        json={"username": username, "password": password},
    )
    response.raise_for_status()
    body = response.json()
    return Account(id=body["id"], username=body["username"], status=body["status"])