101 lines
2.7 KiB
Ruby
101 lines
2.7 KiB
Ruby
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require File.expand_path(File.dirname(__FILE__) + '/neo')
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class AboutSymbols < Neo::Koan
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def test_symbols_are_symbols
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symbol = :ruby
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assert_equal true, symbol.is_a?(Symbol)
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end
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def test_symbols_can_be_compared
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symbol1 = :a_symbol
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symbol2 = :a_symbol
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symbol3 = :something_else
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assert_equal true, symbol1 == symbol2
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assert_equal false, symbol1 == symbol3
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end
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def test_identical_symbols_are_a_single_internal_object
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symbol1 = :a_symbol
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symbol2 = :a_symbol
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assert_equal true, symbol1 == symbol2
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assert_equal true, symbol1.object_id == symbol2.object_id
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end
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def test_method_names_become_symbols
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symbols_as_strings = Symbol.all_symbols.map { |x| x.to_s }
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assert_equal true, symbols_as_strings.include?("test_method_names_become_symbols")
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end
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# THINK ABOUT IT:
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#
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# Why do we convert the list of symbols to strings and then compare
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# against the string value rather than against symbols?
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in_ruby_version("mri") do
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RubyConstant = "What is the sound of one hand clapping?"
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def test_constants_become_symbols
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all_symbols_as_strings = Symbol.all_symbols.map { |x| x.to_s }
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assert_equal true, all_symbols_as_strings.include?("RubyConstant")
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end
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end
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def test_symbols_can_be_made_from_strings
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string = "catsAndDogs"
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assert_equal :catsAndDogs, string.to_sym
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end
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def test_symbols_with_spaces_can_be_built
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symbol = :"cats and dogs"
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assert_equal :"cats and dogs".to_sym, symbol
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end
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def test_symbols_with_interpolation_can_be_built
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value = "and"
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symbol = :"cats #{value} dogs"
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assert_equal :"cats and dogs".to_sym, symbol
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end
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def test_to_s_is_called_on_interpolated_symbols
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symbol = :cats
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string = "It is raining #{symbol} and dogs."
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assert_equal "It is raining cats and dogs.", string
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end
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def test_symbols_are_not_strings
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symbol = :ruby
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assert_equal false, symbol.is_a?(String)
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assert_equal false, symbol.eql?("ruby")
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end
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def test_symbols_do_not_have_string_methods
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symbol = :not_a_string
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assert_equal false, symbol.respond_to?(:each_char)
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assert_equal false, symbol.respond_to?(:reverse)
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end
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# It's important to realize that symbols are not "immutable
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# strings", though they are immutable. None of the
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# interesting string operations are available on symbols.
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def test_symbols_cannot_be_concatenated
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# Exceptions will be pondered further down the path
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assert_raise(NoMethodError) do
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:cats + :dogs
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end
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end
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def test_symbols_can_be_dynamically_created
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assert_equal :catsdogs, ("cats" + "dogs").to_sym
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end
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# THINK ABOUT IT:
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#
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# Why is it not a good idea to dynamically create a lot of symbols?
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end
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