Improved group_name and channel_name validation error messages.

[ericls]

This is to include the maximum length in the error message when validating group and channels names.
Also found that invalid_name_error is defined but never used. This PR also utilizes that to format error messages.
Some tests were added.

Closes #1229.

[carltongibson]

Hi @ericls.

Thanks for your input here. Are you up for finishing this PR off? (Please let us know. 🙂)

There's a few problems with the new MAX_NAME_LENGTH variable.

• Nothing fails if I change it to say 200, or 50. (Or any other value.)
• Surely it needs to be doing something in match_type_and_length()?
• It should probably be moved to an attribute of BaseChannelLayer so it can be overridden in a subclass.
• Yes, it should be documented as @jpic notes.

I'm not sure I mind the tests as you've written them. (Yes, testing format() seems unnecessary.) We can come back to that if you resolve the other issues though.

No need to adjust the existing error handling in this PR. Raising the TypeError is fine.

[ericls]

Hi @carltongibson and @jpic,
Sorry for the delay and thanks for the review and suggestions.
I do plan to finish this PR by the end of tomorrow (eastern time)

Outdated

[carltongibson]

This needs to be rebased after #1792

[ericls]

This needs to be rebased after #1792

Thanks for the reminder, I've rebased the changes on top of the latest main. I've also noticed that the current error message is missing a .format() call, and would throw TypeError: 'str' object is not callable

[carltongibson]

Great. Thanks @ericls. 👍