Refactor assert x == y into self.assertEqual(x, y)

[sobolevn]

I think the second option is better because:

1. It does not get removed in -O mode
2. It has much cleaner error message

[isidentical]

Are there any tests that use assert x == y in an unittest? I've never seen such code, but if you have any examples feel free to add an implementation for that.

[sobolevn]

CPython has lots of assert tests with unittest.
Examples:

• https://github.com/python/cpython/blob/main/Lib/test/test_types.py#L229-L230
• https://github.com/python/cpython/blob/main/Lib/test/test_typing.py#L4109-L4110
• https://github.com/python/cpython/blob/main/Lib/test/test_dis.py#L1432
• etc

I think that this is an error, but I would not push this change there 🙂
I will send a PR with this feature somewhere this week, though 👍

[isidentical]

Ah, TIL. Would gladly accept a PR about it.

[sobolevn]

I think that there are some important limitations to this rule:

1. It should be limited to ast.[Async]FunctionDef scope inside ast.ClassDef
2. We must be sure that it is a test function. For now, I am going to detect a test as "a method" with test prefix or postfix
3. We must be sure that self argument exists