# by Greg Houston
# http://ghouston.blogspot.com/

require 'test/unit'

class Test_Hash < Test::Unit::TestCase
  def test_hash_clones_string_key
    # demonstrates the behavior of Ruby's Hash
    #
    # when Ruby's Hash gets a String for a key, it appears to create a
    # new String with the same contents to use as the original string.
    #
    # unfortunately any overridden methods in the original string's singleton_class
    # are lost to the Hash key.

    h = Hash.new
    k = "key"
    class << k
      def foo; 'foo'; end
    end

    h[k] = "value"
    assert( k.respond_to?( :foo ), "k should have singleton_class method #foo" )
    assert( !h.keys[0].respond_to?( :foo ), "key should not have singleton_class method #foo" )

    ids = h.collect { |key,value| key.object_id }
    assert( !ids.include?( k.object_id ), "key in hash should have a different object_id" )
  end
end

=begin
>ruby try_hash_string_key.rb
Loaded suite try_hash_string_key
Started
.
Finished in 0.0 seconds.

1 tests, 3 assertions, 0 failures, 0 errors
>Exit code: 0
=end