Consider using pytest-mypy-plugins

[sobolevn]

Hi! Thanks for this awesome project!

I am TypedDjango team member, we maintain types for, well, django. And we do pretty much the same job.

For example, we also test our types the similar way as you do in tests/. We even created a tool called pytest-mypy-plugins (announcing post) to help us with this task. Maybe it will be also helpful to you as well.

That's how the simplest test looks like:

- case: compose_two_wrong_functions
  main: |
    from returns.functions import compose

    def first(num: int) -> float:
        return float(num)

    def second(num: float) -> str:
        return str(num)

    reveal_type(compose(first, second)(1))  # N: builtins.str*

Ask any questions you have!