public async Task TwoContents_SendsWithCorrectContent()
                {
                    var handler = Handler();
                    var message = Message();

                    message = new EmailMessage(message.From, message.To, message.Subject,
                                               new EmailContent[]
                    {
                        EmailContent.PlainText("pt"),
                        EmailContent.Html("html"),
                    });

                    await Service(handler).Send(message);

                    var content = await handler.SendAsync_InputRequest !.Content !
                                  .ReadAsStringAsync();

                    Assert.Contains("\"content\":[{\"type\":\"text/plain\",\"value\":\"pt\"},{\"type\":\"text/html\",\"value\":\"html\"}]",
                                    content);
                }