Call before and call after - Python decorators

call_before_after.py

from functools import wraps


def call_before(before_func, *args, **kwargs):
    def call_before_decorator(func):
        @wraps(func)
        def wrapping(*args2, **kwargs2):
            before_func(*args, **kwargs)
            return func(*args2, **kwargs2)
        return wrapping
    return call_before_decorator


def call_after(after_func, *args, **kwargs):
    def call_after_decorator(func):
        @wraps(func)
        def wrapping(*args2, **kwargs2):
            try:
                result = func(*args2, **kwargs2)
            finally:
                after_func(*args, **kwargs)
            return result
        return wrapping
    return call_after_decorator

# And use them chained:

def log_enter_exit(logger, message=""):
    def enter_exit_decorator(func):
        @wraps(func)
        @call_before(logger.debug, "Calling %s - %s", func.__name__, message)
        @call_after(logger.debug, "Called %s - %s", func.__name__, message)
        def wrapping(*args, **kwargs):
            return func(*args, **kwargs)
        return wrapping
    return enter_exit_decorator


# Tests, because tests:

import mock
import unittest

from commons.decorators import *


class DecoratorsTestCase(unittest.TestCase):

    def test_callbefore(self):
        a = []

        def append(where, what):
            where.append(what)

        @call_before(append, a, 3)
        def extend(where, what):
            where.extend(what)
            return where

        self.assertEqual(extend(a, [4, 5]), [3, 4, 5])
        self.assertEqual(extend(a, [6]), [3, 4, 5, 3, 6])
        self.assertEqual(extend([], [1, 2]), [1, 2])
        self.assertEqual(a, [3, 4, 5, 3, 6, 3])

    def test_callafter(self):
        a = []

        def append(where, what):
            where.append(what)

        @call_after(append, a, 6)
        def extend(where, what):
            where.extend(what)
            return list(where)

        self.assertEqual(extend(a, [4, 5]), [4, 5])
        self.assertEqual(a, [4, 5, 6])
        self.assertEqual(extend(a, [7]), [4, 5, 6, 7])
        self.assertEqual(a, [4, 5, 6, 7, 6])
        self.assertEqual(extend([], [1, 2]), [1, 2])
        self.assertEqual(a, [4, 5, 6, 7, 6, 6])

    def test_log_enter_exit(self):
        logger = mock.Mock()
        messages = []

        def debug(pattern, *args, **kwargs):
            messages.append(pattern % args)
        logger.debug.side_effect = debug

        logger.debug("Testing my %s", "mock")
        self.assertEqual(messages[0], "Testing my mock")

        @log_enter_exit(logger, "Whoaa")
        def append(arg):
            messages.append(arg)
            return 3

        self.assertEqual(append(666), 3)
        self.assertEqual(messages[-3], "Calling append - Whoaa")
        self.assertEqual(messages[-2], 666)
        self.assertEqual(messages[-1], "Called append - Whoaa")