from collections import Counter
from gc import get_objects
import pytest

def difference_tracked_objects(func, specific_object=None):
    # rather trivial attempt at finding memory leaks, this attempt does not always work! 
    # That's why I created a custom class and used the "specific_object".
    before = Counter()
    after = Counter()
    before.update(map(type, get_objects()))
    func()
    after.update(map(type, get_objects()))
    if specific_object is None:
        return after - before
    else:
        leftover = after[specific_object] - before[specific_object]
        if leftover:
            return Counter({specific_object: leftover})
        else:
            return Counter()

class Test(object):
    def __init__(self, value):
        self.value = value

def testfunc():
    func = lambda x: x.value + ''
    v = Test(10)
    with pytest.raises(TypeError):
        func(v)

difference_tracked_objects(testfunc, Test)
# Counter() (on pytest < 3.0.2)
# Counter({<class '__main__.Test'>: 1}) (on pytest == 3.0.2) <-- looks like memory leak