    def test_auth_plain
      sock = FakeSocket.new
      smtp = Net::SMTP.new 'localhost', 25
      smtp.instance_variable_set :@socket, sock
      assert smtp.auth_plain("foo", "bar").success?
      assert_equal "AUTH PLAIN AGZvbwBiYXI=\r\n", sock.write_io.string
    end
The software uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.