python_koans/python2/koans/about_monkey_patching.py at master · arksega/python_koans · GitHub

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#!/usr/bin/env python

# -*- coding: utf-8 -*-

# Related to AboutOpenClasses in the Ruby Koans

from runner.koan import *

class AboutMonkeyPatching(Koan):

class Dog(object):

def bark(self):

return "WOOF"

def test_as_defined_dogs_do_bark(self):

fido = self.Dog()

self.assertEqual(__, fido.bark())

# ------------------------------------------------------------------

# Add a new method to an existing class.

def test_after_patching_dogs_can_both_wag_and_bark(self):

def wag(self):

return "HAPPY"

self.Dog.wag = wag

fido = self.Dog()

self.assertEqual(__, fido.wag())

self.assertEqual(__, fido.bark())

# ------------------------------------------------------------------

def test_most_built_in_classes_cannot_be_monkey_patched(self):

try:

int.is_even = lambda self: (self % 2) == 0

except StandardError as ex:

self.assertMatch(__, ex[0])

# ------------------------------------------------------------------

class MyInt(int):

pass

def test_subclasses_of_built_in_classes_can_be_be_monkey_patched(self):

self.MyInt.is_even = lambda self: (self % 2) == 0

self.assertEqual(____, self.MyInt(1).is_even())

self.assertEqual(____, self.MyInt(2).is_even())