Comment by gorgoiler

Hah, I swing the other way! If module foo had a function bar then my test is in module test_foo and the test is called test_bar.

Nine times out of ten this is the only test, which is mostly there to ensure the code gets exercised in a sensible way and returns a thing, and ideally to document and enforce the contract of the function.

What I absolutely agree with you on is that being able to describe this contract alongside the function itself is far more preferable. It’s not quite literate programming but tools like Python’s doctest offer a close approximation to interleaving discourse with machine readable implementation:

  def double(n: int) -> int:
    “””Increase by 100%

    >>> double(7)
    14
    “””
    return 2 * n