assert_trace does not work correctly with functions that use the same decorator

[thepabloaguilar]

Bug report

What's wrong

Our assert_trace from pytest plugin doesn't work correctly when two or more different functions are using the same decorator, it not considers that those functions are different! See the example below:

def test_two_functios_using_same_decorator(returns: ReturnsAsserts):
    def decorator(func):
        def decorated(*args, **kwargs):
            return func(*args, **kwargs)
        return decorated

    @decorator
    def func_one():
        return Success(42)

    @decorator
    def func_two():
        return Success(42)

    with returns.assert_trace(Success, func_one):
        func_two()

That test should fail because we want to assert the Success creation inside func_one, but I'm calling func_two and the test is passing!

How is that should be

Our pytest plugin should consider that those functions are different!

System information

• python version: 3.9
• returns version: 0.16.0

[sobolevn]

What if we use @wraps on def decorated? 🤔

[thepabloaguilar]

Also doesn't work, I tested with safe too (safe uses wraps)
wraps just keep some metadata like name and docstring. But if we get the code from them they are the same

[thepabloaguilar]

I know how to solve this issue! Reading the Python docs I discovered that wrapped functions has the __wrapped__ attribute which we can use to get the "original" function!

The users just need to pay attention to use the wraps decorator inside their decorators!

Docs: https://docs.python.org/3/library/functools.html#functools.update_wrapper

[sobolevn]

Let's add this to the docs :)

[thepabloaguilar]

I made the fix and broke other part 😆

The thing is, fixing this (with the actual code ive made) we won't be able to handle creations within decorators cause we're getting the most inner function, @safe won't work for example:

@safe
def _safe_decorated_function(return_failure: bool = False):
    if return_failure:
        raise ValueError('Function failed')

def test_something():
    with returns.assert_trace(container_type, _safe_decorated_function):
        _safe_decorated_function(True)

Failure is being created inside safe and not _safe_decorated_function

Suggestions?

[sobolevn]

Suggestions?

No :(