class DictKeyMatcher
  defm match(expected, actual)
    return has_key(actual, expected)
  end

  defm failure_message_for_match(expected, actual)
    return "expected object to have key “#{expected}”"
  end

  defm failure_message_for_mismatch(expected, actual)
    return "expected object to not have key “#{expected}”"
  end
end