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 __, not_like_a_string.to_s end def test_normally_objects_cannot_be_used_where_strings_are_expected assert_raise(___) 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 __, like_a_string.to_str end def test_to_str_allows_objects_to_be_treated_as_strings assert_equal __, 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 __, acts_like_a_string?(CanNotBeTreatedAsString.new) assert_equal __, acts_like_a_string?(CanBeTreatedAsString.new) end end