##
# Hash(Ext) Test

assert('Hash#merge!') do
  a = { 'abc_key' => 'abc_value', 'cba_key' => 'cba_value' }
  b = { 'cba_key' => 'XXX',  'xyz_key' => 'xyz_value' }

  result_1 = a.merge! b
  
  a = { 'abc_key' => 'abc_value', 'cba_key' => 'cba_value' }
  result_2 = a.merge!(b) do |key, original, new|
    original
  end

  assert_equal({'abc_key' => 'abc_value', 'cba_key' => 'XXX',
               'xyz_key' => 'xyz_value' }, result_1)
  assert_equal({'abc_key' => 'abc_value', 'cba_key' => 'cba_value',
               'xyz_key' => 'xyz_value' }, result_2)
end

assert('Hash#values_at') do
  h = { "cat" => "feline", "dog" => "canine", "cow" => "bovine" }
  assert_equal ["bovine", "feline"], h.values_at("cow", "cat")
end