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