47 lines
1.2 KiB
Ruby
47 lines
1.2 KiB
Ruby
require 'edgecase'
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class AboutNil < EdgeCase::Koan
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def test_nil_is_an_object
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assert nil.is_a?(Object), "Unlike NULL in other languages"
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end
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def test_you_dont_get_null_pointer_errors_when_calling_methods_on_nil
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#
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# What is the Exception that is thrown when you call a method that
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# does not exist?
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#
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# Hint: launch irb and try the code in the block below.
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#
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# Don't be confused by the code below yet. It's using blocks
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# which are explained later on in about_blocks.rb. For now,
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# think about it like running nil.some_method_nil_doesnt_know_about
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# in a sandbox and catching the error class into the exception
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# variable.
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#
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exception = assert_raise(___) do
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nil.some_method_nil_doesnt_know_about
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end
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#
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# What is the error message itself? What substring or pattern could
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# you test against in order to have a good idea what the string is?
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#
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assert_match /__/, exception.message
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end
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def test_nil_has_a_few_methods_defined_on_it
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assert_equal __, nil.nil?
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assert_equal __, nil.to_s
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assert_equal __, nil.inspect
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# THINK ABOUT IT:
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#
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# Is it better to use
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# obj.nil?
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# or
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# obj == nil
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# Why?
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end
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end
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