Test: Add coverage for wheel filename normalization.

[pelson]

I noticed that #387 did not include a test for _ in the wheel name, nor for anything with upper case characters. This kind of filename can be generated with python -m build and pip wheel --no-deps.

cc @pfmoore as the author of the original PR

[pfmoore]

Hmm, are wheel filenames with uppercase in them even valid? https://packaging.python.org/specifications/binary-distribution-format/ says

In distribution names, any run of -_. characters (HYPHEN-MINUS, LOW LINE and FULL STOP) should be replaced with _ (LOW LINE). This is equivalent to PEP 503 normalisation followed by replacing - with _.

That's not actually self-consistent as PEP 503 converts everything to lower case, whereas the text before that doesn't say that should happen. The reference to PEP 503 wasn't in the original wheel PEP (it was added in pypa/packaging.python.org#844, which references https://discuss.python.org/t/escaping-versions-for-wheel-sdist-and-dist-info-names/5605).

Either way, I think we probably have to accept that we'll see mixed-case distribution names in the wild, and normalising them when parsing is the correct thing to do, so these tests make sense even if it turns out that they are testing how the code handles technically-invalid input.

[brettcannon]

Thanks!