TestClient seems to ignore explicit client address / host header

[bjd183]

The docs indicate that the test client host header can be set as follows:

Change client address
By default, the TestClient will set the client host to "testserver" and the port to 50000.

You can change the client address by setting the client attribute of the TestClient instance:


client = TestClient(app, client=('localhost', 8000))

When using TrustedHostMiddleware with ALLOWED_HOSTS=['localhost'], I receive a 400 Invalid host header when calling client.get(url).

Setting the client tuple appears to have no effect because httpx sets the host header to match url.netloc here when creating a request. The workaround is to use TestClient(app, base_url='http://localhost') instead of TestClient(app, client=('localhost', 8000)).

The TestClient passes the client tuple to the TestClientTransport which, in turn, sets the value into the scope variable for use by asgi. It's not clear which of these two approaches is intended or preferred, whether they are compatible or mutually exclusive. Is there something I am missing or not understanding?

[Kludex]

You should be using headers instead of client.

[bjd183]

What, then, is the purpose of client if it's not what is described in the docs?

[Kludex]

Well, actually...

It seems to me that it was a mistake to create this client, if it's actually used in such a way by httpx.

Maybe we should have used the same strategy to pass it to ASGI client value. 🤔