use diff for multiline bytes

[RonnyPfannschmidt]

What's the problem this feature will solve?

unlike multiline stings, bytes get diffed as full value

Describe the solution you'd like

instead of

   def test_wheelinfo():
        wi = metadata.get_wheel_info()
        print(wi)
>       assert wi == WHEEL_DEFAULT_META
E       AssertionError: assert b'Wheel-Versi... py3-none-any' == b'Wheel-Versi... py3-none-any'
E         At index 79 diff: b'3' != b'2'
E         Use -v to get the full diff

i want to see sometihing like

______________________________________________ test_wheelinfo ______________________________________________

    def test_wheelinfo():
        wi = metadata.get_wheel_info()
        print(wi)
>       assert wi.decode() == WHEEL_DEFAULT_META
E       AssertionError: assert 'Wheel-Versio... py3-none-any' == 'Wheel-Versio... py3-none-any'
E         Skipping 69 identical leading characters in diff, use -v to show
E           ue
E         - Tag: py27-none-any
E           Tag: py3-none-any

[The-Compiler]

Also see #5199 - I tend to agree with what @nicoddemus has said there:

I'm not sure what to do here; your byte strings are actually text in this example, but we cannot assume this in general; for example the byte strings might be an image, in which case trying to display any part of it in the assertion message will only result in garbage. I think it is reasonable to expect that users do the decoding themselves, as they know best what are the underlying contents of the byte string.

Personally I'd prefer if Python's bytes-repr would not show ascii data at all (since for "real" binary data, it's confusing). I feel like we should resist the temptation to interpret even more into data we know nothing about.

[RonnyPfannschmidt]

true, maybe a pytest plugin with more fun bytes diffs needs to be made

closing as not fit for core