86 lines
1.6 KiB
Ruby
86 lines
1.6 KiB
Ruby
require File.expand_path(File.dirname(__FILE__) + '/edgecase')
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class AboutInheritance < EdgeCase::Koan
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class Dog
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attr_reader :name
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def initialize(name)
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@name = name
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end
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def bark
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"WOOF"
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end
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end
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class Chihuahua < Dog
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def wag
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:happy
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end
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def bark
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"yip"
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end
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end
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def test_subclasses_have_the_parent_as_an_ancestor
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assert_equal __, Chihuahua.ancestors.include?(Dog)
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end
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def test_all_classes_ultimately_inherit_from_object
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assert_equal __, Chihuahua.ancestors.include?(Object)
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end
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def test_subcases_inherit_behavior_from_parent_class
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chico = Chihuahua.new("Chico")
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assert_equal __, chico.name
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end
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def test_subclasses_add_new_behavior
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chico = Chihuahua.new("Chico")
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assert_equal __, chico.wag
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assert_raise(___) do
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fido = Dog.new("Fido")
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fido.wag
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end
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end
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def test_subclasses_can_modify_existing_behavior
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chico = Chihuahua.new("Chico")
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assert_equal __, chico.bark
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fido = Dog.new("Fido")
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assert_equal __, fido.bark
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end
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# ------------------------------------------------------------------
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class BullDog < Dog
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def bark
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super + ", GROWL"
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end
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end
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def test_subclasses_can_invoke_parent_behavior_via_super
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ralph = BullDog.new("Ralph")
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assert_equal __, ralph.bark
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end
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# ------------------------------------------------------------------
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class GreatDane < Dog
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def growl
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super.bark + ", GROWL"
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end
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end
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def test_super_does_not_work_cross_method
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george = GreatDane.new("George")
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assert_raise(___) do
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george.growl
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end
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end
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end
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