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about_to_str.rb
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about_to_str.rb
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require File.expand_path(File.dirname(__FILE__) + '/neo')
class AboutToStr < Neo::Koan
class CanNotBeTreatedAsString
def to_s
"non-string-like"
end
end
def test_to_s_returns_a_string_representation
not_like_a_string = CanNotBeTreatedAsString.new
assert_equal "non-string-like", not_like_a_string.to_s
end
def test_normally_objects_cannot_be_used_where_strings_are_expected
assert_raise(TypeError) do
File.exist?(CanNotBeTreatedAsString.new)
end
end
# ------------------------------------------------------------------
class CanBeTreatedAsString
def to_s
"string-like"
end
def to_str
to_s
end
end
def test_to_str_also_returns_a_string_representation
like_a_string = CanBeTreatedAsString.new
assert_equal "string-like", like_a_string.to_str
end
def test_to_str_allows_objects_to_be_treated_as_strings
assert_equal false, File.exist?(CanBeTreatedAsString.new)
end
# ------------------------------------------------------------------
def acts_like_a_string?(string)
string = string.to_str if string.respond_to?(:to_str)
string.is_a?(String)
end
def test_user_defined_code_can_check_for_to_str
assert_equal false, acts_like_a_string?(CanNotBeTreatedAsString.new)
assert_equal true, acts_like_a_string?(CanBeTreatedAsString.new)
end
end