Allow usage of `CoversNothing` on test class method when test class has `Covers*` attribute without warning

[jnoordsij]

With #6170 a warning was added, that will warn if a test combines CoversNothing and Covers* on a target, as it may suggest improper attribute usage by the user.

However, I think there is still a potentially valid case where this may happen:

• have a test class with a Covers* attribute applied to it
• have a test method within the class with the CoversNothing to 'override' the class-level attribute declaration

For my use-case, I combine these in tests where I'm testing one single class, but have some sanity-like test not related directly to code execution of this class. This is mainly just a nice way of adding some metadata, but I can think of similar examples where this may be even more viable. Therefore I've opted to create this issue to gather some feedback and perhaps traction of people with similar appliances to see if changing this is viable.

Note there may be more target combinations that could potentially be considered valid cases of combining these two attributes (or others) in some way.

[jnoordsij]

(Side note: I really like the efforts made in #6170 !)

[sebastianbergmann]

For me, the problem here is that #[CoversNothing] can be used on a class and on a method whereas the other #[Covers*] attributes can only be used on a class.

I am not convinced that there is a valid use case for using #[CoversNothing] on a method and therefore would rather sunset support for using #[CoversNothing] on a method.

[jnoordsij]

Ah I see, that makes a lot of sense as well. I do agree that my use case is mostly just nitpicking and not really useful in terms of functionality. If this issue receives no further traction in the next couple of weeks, I fully agree that the best course of action would probably be to deprecate targeting methods with #[CoversNothing] as there's probably no point for that after #6170.