dictdiff.py

def dictdiff(f):
    def wrapper(a, b, *args, **kwargs):
        try:
            f(a, b, *args, **kwargs)
        except AssertionError as e:
            if isinstance(a, dict) and isinstance(b, dict):
                a_items = a.items()
                b_items = b.items()
                in_a = [i for i in a_items if i not in b_items]
                in_b = [i for i in b_items if i not in a_items]
                e.args = tuple(["\nIn first dict: %s\nIn second dict: %s" % (
                    in_a,
                    in_b
                )] + list(e.args[1:]))
            raise e
    return wrapper