python_koans/python3/koans/about_inheritance.py at master · arksega/python_koans · GitHub

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#!/usr/bin/env python

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

from runner.koan import *

class AboutInheritance(Koan):

class Dog:

def __init__(self, name):

self._name = name

@property

def name(self):

return self._name

def bark(self):

return "WOOF"

class Chihuahua(Dog):

def wag(self):

return "happy"

def bark(self):

return "yip"

def test_subclasses_have_the_parent_as_an_ancestor(self):

self.assertEqual(__, issubclass(self.Chihuahua, self.Dog))

def test_this_all_classes_in_python_3_ultimately_inherit_from_object_class(self):

self.assertEqual(__, issubclass(self.Chihuahua, object))

# Note: This isn't the case in Python 2. In that version you have

# to inherit from a built in class or object explicitly

def test_instances_inherit_behavior_from_parent_class(self):

chico = self.Chihuahua("Chico")

self.assertEqual(__, chico.name)

def test_subclasses_add_new_behavior(self):

chico = self.Chihuahua("Chico")

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

fido = self.Dog("Fido")

with self.assertRaises(___): fido.wag()

def test_subclasses_can_modify_existing_behavior(self):

chico = self.Chihuahua("Chico")

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

fido = self.Dog("Fido")

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

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

class BullDog(Dog):

def bark(self):

return super().bark() + ", GRR"

# Note, super() is much simpler to use in Python 3!

def test_subclasses_can_invoke_parent_behavior_via_super(self):

ralph = self.BullDog("Ralph")

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

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

class GreatDane(Dog):

def growl(self):

return super().bark() + ", GROWL"

def test_super_works_across_methods(self):

george = self.GreatDane("George")

self.assertEqual(__, george.growl())

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

class Pug(Dog):

def __init__(self, name):

pass

class Greyhound(Dog):

def __init__(self, name):

super().__init__(name)

def test_base_init_does_not_get_called_automatically(self):

snoopy = self.Pug("Snoopy")

with self.assertRaises(___): name = snoopy.name

def test_base_init_has_to_be_called_explicitly(self):

boxer = self.Greyhound("Boxer")

self.assertEqual(__, boxer.name)

python_koans/python3/koans/about_inheritance.py at master · arksega/python_koans · GitHub

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