// Test GraphService.GetMyEmailAddress method. 
        // Gets the email address of the test account.
        // Success: Retrieved email address matches test account's email address.
        public async Task GetMyEmailAddress()
        {
            // Arrange
            GraphService graphService = new GraphService();
            string emailAddress = null;

            // Act
            emailAddress = await graphService.GetMyEmailAddress(accessToken);

            // Assert
            Assert.IsTrue(emailAddress.ToLower() == userName.ToLower(), emailAddress.ToString());

        }
        // Test GraphService.SendEmail method. 
        // Sends an email to the test account from the test account.
        // Success: Retrieved message body matches sent message body.
        public async Task SendEmail()
        {
            // Arrange
            string testBody = Guid.NewGuid().ToString();
            GraphService graphService = new GraphService();
            List<Recipient> recipientList = new List<Recipient>();
            recipientList.Add(new Recipient
            {
                EmailAddress = new UserInfo
                {
                    Address = userName
                }
            });
            Message message = new Message
            {
                Body = new ItemBody
                {
                    Content = "<html><body>" + testBody + "</body></html>",
                    ContentType = "HTML"
                },
                Subject = "Test email from ASP.NET 4.6 Connect sample",
                ToRecipients = recipientList
            };
            MessageRequest email = new MessageRequest
            {
                Message = message,
                SaveToSentItems = true
            };

            try
            {
                // Act
                string response = await graphService.SendEmail(accessToken, email);
            }

            // Test action will throw an exception when it tries to return resource string.
            // So catch the exception when the operation is complete, and then retrieve the email.
            catch (Exception e)
            {
                if (e.HResult == -2147024894)
                {
                    var mailBody = await GetLastEmail(accessToken);

                    // Assert
                    Assert.IsTrue(mailBody == testBody, mailBody);
                    return;
                }
                else
                {
                    Assert.Fail(e.InnerException.ToString());
                }
            }
            Assert.Fail();
        }