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.
PHP 8.2 is supposed to deprecate the use of `['self', 'functionname']` for callables, suggesting the use of `[self::class, 'functionname']` instead. We made this change in a recent PR, and, while I'm thinking about it, I'll fix the remaining 2 modules with this construction. Vlookup is already adequately covered in unit tests. Reader/Xls/MD5 is not; a unit test is added.
Adrien Crivelli
oleibman