invalid format of client's host in testclient

[Kludex]

Discussed in https://github.com/encode/starlette/discussions/2109

^{Originally posted by pjknkda April 3, 2023} According to ASGI specification, scope["client"] for HTTP and Websocket protocol should have its host value in either IPv4 or IPv6 address formats.

However, in starlette/testclient.py, the _TestClientTransport set its host value to "testclient" and breaks applications that expect IPv4 or IPv6 address formats during tests.

https://github.com/encode/starlette/blob/f7bf74194358cceb5708f758989df89240c0c1aa/starlette/testclient.py#L246

https://github.com/encode/starlette/blob/f7bf74194358cceb5708f758989df89240c0c1aa/starlette/testclient.py#L264

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[aminalaee]

Is it even possible to get the client IP, port at this stage when the request is not made? I think you could allow specifying the client IP, port but not get them when the request is not done (at least not in a reliable way)

And also the spec mentions: Optional; if missing defaults to None and I think that might make more sense when working with TestClient, because both of IP, Port in scope["client"] are invalid.

[Kludex]

PR is welcome to set scope["client"] to None.

But I'll preemptively close this issue. I don't think it is a big deal.

[toxadx]

Setting to None and to ['testclient', 50000] are both bad solutions. I propose to pass transport to TestClient constructor, so that it will be possible to subclass from _TestClientTransport and implement custom logic (like setting scope["client"] to None or to ['::1', 12345]).

[Kludex]

PR welcome to add client parameter to TestClient.

[iudeen]

I have created a PR #2810 for this...any idea how this can be tested? How was this issue first identified?