Test Client constructor accepts headers that are ignored/overwitten

[Paul Garner]

At first glance it seems like you could supply 'default' headers that are applied to every request when instantiating a test Client...

class Client(ClientMixin, RequestFactory):
    def __init__(
        self,
        enforce_csrf_checks=False,
        raise_request_exception=True,
        *,
        headers=None,
        query_params=None,
        **defaults,
    ):
        super().__init__(headers=headers, query_params=query_params, **defaults)
        self.handler = ClientHandler(enforce_csrf_checks)
        self.raise_request_exception = raise_request_exception
        self.exc_info = None
        self.extra = None
        self.headers = None

​https://github.com/django/django/blob/main/django/test/client.py#L1059

However passing headers arg is completely useless, because the request methods do this:

    def get(
        self,
        path,
        data=None,
        follow=False,
        secure=False,
        *,
        headers=None,
        query_params=None,
        **extra,
    ):
        """Request a response from the server using GET."""
        self.extra = extra
        self.headers = headers
        response = super().get(
            path,
            data=data,
            secure=secure,
            headers=headers,
            query_params=query_params,
            **extra,
        )

​https://github.com/django/django/blob/main/django/test/client.py#L1121

This seems like a bad design? Shouldn't the get etc methods merge their arg headers with self.headers without overwriting it? (and same for extra)

I'm happy to submit a PR for this, assuming things aren't the way they are for some necessary reason that I've missed.

[Paul Garner]

despite looking wrong, it works as intended since the headers are passed into RequestFactory constructor which adds them to defaults

so ultimately the args from the get call do get merged on top, just in a roundabout way