46 lines
946 B
Ruby
46 lines
946 B
Ruby
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require File.expand_path(File.dirname(__FILE__) + '/edgecase')
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class AboutOpenClasses < EdgeCase::Koan
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class Dog
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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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def test_as_defined_dogs_do_bark
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fido = Dog.new
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assert_equal __, fido.bark
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end
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# ------------------------------------------------------------------
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# Open the existing Dog class and add a new method.
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class Dog
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def wag
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"HAPPY"
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end
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end
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def test_after_reopening_dogs_can_both_wag_and_bark
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fido = Dog.new
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assert_equal __, fido.wag
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assert_equal __, fido.bark
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end
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# ------------------------------------------------------------------
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class ::Integer
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def even?
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(self % 2) == 0
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end
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end
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def test_even_existing_built_in_classes_can_be_reopened
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assert_equal __, 1.even?
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assert_equal __, 2.even?
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end
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# NOTE: To understand why we need the :: before Integer, you need to
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# become enlightened about scope.
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end
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