Using dict to provide ids for pytest.mark.parametrize

[pepoluan]

As it is right now, to provide non-default test IDs when using pytest.mark.parametrize, one must use the ids keyword arg.

However, a thought occurred to me: What if we supply a dict to parametrize's argvalues, and from that dict, use the keys as the don-default test IDs?

For example, rather than:

    @pytest.mark.parametrize(
        "command", [
            "RCPT",
            "RCPT <anne@example.com>",
            "RCPT TO:",
            "RCPT TO: <bart@example.com> SIZE=1000",
        ],
        ids=["noarg", "noto", "noaddr", "params"]
    )

we can supply it more succinctly like so:

    @pytest.mark.parametrize(
        "command", {
            "noarg": "RCPT",
            "noto": "RCPT <anne@example.com>",
            "noaddr": "RCPT TO:",
            "params": "RCPT TO: <bart@example.com> SIZE=1000",
        }
    )

Users who absolutely need ordering can still use the first one, or use OrderedDict (or standard dict in Python>=3.7, where dict ordering became a language feature.)

[The-Compiler]

There isn't really an agreement on what dicts in parametrize should mean - see #7568 and related discussions.

Note that you can already use pytest.param:

    @pytest.mark.parametrize(
        "command", [
            pytest.param("RCPT", id="noarg"),
            pytest.param("RCPT <anne@example.com>", id="noto"),
            pytest.param("RCPT TO:", id="noattr"),
            pytest.param("RCPT TO: <bart@example.com> SIZE=1000", id="params"),
        ],
    )