public async Task GetAsyncTestUnhappy()
        {
            // Arrange
            var mockMailMessageRepository = GetDefaultIMailMessageRepositoryInstance();
            var mockIUnitOfWork           = GetDefaultIUnitOfWorkInstance();
            var mockCoordinatorRepository = GetDefaultICoordinatorRepositoryInstance();

            var mailMessageId = 1;
            var service       = new MailMessageService(mockMailMessageRepository.Object, mockCoordinatorRepository.Object, mockIUnitOfWork.Object);

            // Act
            MailMessageResponse result = await service.GetByIdAsync(mailMessageId);

            var message = result.Message;

            // Assert
            message.Should().Be("mail message not found");
        }
        public async Task GetAsyncTestHappy()
        {
            // Arrange
            var mockMailMessageRepository = GetDefaultIMailMessageRepositoryInstance();
            var mockIUnitOfWork           = GetDefaultIUnitOfWorkInstance();
            var mockCoordinatorRepository = GetDefaultICoordinatorRepositoryInstance();

            MailMessage mailMessage   = new MailMessage();
            var         mailMessageId = 1;

            mailMessage.Id = mailMessageId;

            mockMailMessageRepository.Setup(r => r.FindById(mailMessageId))
            .Returns(Task.FromResult <MailMessage>(mailMessage));

            var service = new MailMessageService(mockMailMessageRepository.Object, mockCoordinatorRepository.Object, mockIUnitOfWork.Object);

            // Act
            MailMessageResponse result = await service.GetByIdAsync(mailMessageId);

            // Assert
            Assert.AreEqual(mailMessage, result.Resource);
        }