Change "mixed" declarations to more accurate types in test members; in particular, change those that would be flagged if we were to run Phpstan at level 9 (we currently run level 8). I may or may not follow up with source code (over 700 level-9 problems remain for src), but, as with strict typing, there is no reason to avoid the effort for test members.
It was necessary to update some doc blocks in src to accommodate this change. However, no executable code is touched.
While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
oleibman
Adrien Crivelli
redforks