Moq Callback does not invoke moq that I've setup

Question

My class and method that mocks:

public class EmailService: IEmailService
{
    private readonly ISendGridClient _client;

    public EmailService(ISendGridClient client)
    {
        _client = client;
    }

    public async Task SendAsync(string email, string senderAderess, string senderName, string recipientName, string subject, string content, string htmlContent)
    {
        var from = new EmailAddress(senderAderess, senderName);
        var to = new EmailAddress(email, recipientName);
        var plainContent = content;
        var msg = MailHelper.CreateSingleEmail(from, to, subject, plainContent, htmlContent);

        await _client.SendEmailAsync(msg);
    }
}

And unit test for it

public async void EmailService_SendingEmail_EmailSentSuccessfullyAsync()
{
    var test = 0;

    var mockEmailClient = new Mock<ISendGridClient>();

    mockEmailClient.Setup(x => x.SendEmailAsync(new SendGridMessage(), CancellationToken.None)).Callback(() => test++);

    var emailSender = new EmailService(mockEmailClient.Object);

    await emailSender.SendAsync("[email protected]", "SenderDemo", "Ilya", "EmailServiceUnitTest", "Demo", "Test",
            "<strong>Hello</strong>");

    Assert.Equal(1, test);
}

And the problem is that my mock does not rise my callback method

Probably the issue because of async nature of the method that mocks, but I really need some your help :)

Answer 1

You are mocking

SendEmailAsync(new SendGridMessage(), CancellationToken.None)

But calling

_client.SendEmailAsync(msg) 

So which one is the right one? Also you don't need this test variable. Simply use

 mockEmailClient.Verify(x => x.SendEmailAsync(...), Times.Once)

You could actually write it this way:

   public async Task EmailService_SendingEmail_EmailSentSuccessfullyAsync()
    {
        var mockEmailClient = new Mock<ISendGridClient>();

        mockEmailClient.Setup(x => x.SendEmailAsync(It.IsAny<YourMessageType>()));

        var emailSender = new EmailService(mockEmailClient.Object);

        await emailSender.SendAsync("[email protected]", "SenderDemo", "Ilya", "EmailServiceUnitTest", "Demo", "Test",
            "<strong>Hello</strong>");

        mockEmailClient.Verify(x => x.SendEmailAsync(It.IsAny<YourMessageType>()), Times.Once);
    }