Make ControllerBase.User virtual for unit testability.

[mkArtakMSFT]

This issue is to track a repo wide impacting changes:

Remove the compatibility switches

• Remove compat switch for Enum DataAnnotation localization. In Update package branding to 3.0.0-preview4 #7748 we decided to fix the fact that Enum localization didn't use DataAnnotationLocalizerProvider behind a compat switch because it was a breaking change. For 3.0.0 we should remove that compat switch and only support the new behavior (usage of DataAnnotationLocalizerProvider).

Remove all the obsolete methods

• See Remove obsolete API aspnet/Mvc#6497

Unit testing cleanup

• Make ControllerBase.User virtual for unit testability.

[dougbu]

This looks like the uber-issue for 3.0 😈 But, do we have an issue covering removal of [Obsolete] types and members?

I see #7382 but nothing that covers all of the ~38 [Obsolete] members e.g. the many old constructor overloads in input formatters and model binders or the ActionResult.ExecuteResult(...) overrides.

[mkArtakMSFT]

@pranavkm, what is left here? Are some of these listed items done already?

[pranavkm]

Make ControllerBase.User virtual for unit testability.

I think that's the only one. I'll update the title

[pranavkm]

Looking at "Make ControllerBase.User virtual for unit testability.", it's fairly trivial to assign the User property using ControllerContext. In addition, none of the properties on the ControllerBase type are virtual. I'm going to close this until we get more feedback here.