Messagebox and Unit testing

Question

I\'m trying to find the best way to uncouple messageboxes from my logic so I can properly unittest it. Now I was wondering if it would be enough if I just made a seperate he

Answer 1

"Unit test", in its exact meaning, is a test of atomic behavior. This is not the only kind of code-driven tests you can make for your code. Especially for testing longer scenarios with "Yes/No" dialogs you mention, larger-scale code-driven tests are often more effective than unit tests.

However to be able to write them easier, it would be good not only to create a special service as it was mentioned by Sergii, but also to make its calls asynchronous:

public interface IDialogService
{
    Task ShowYesNoMessageBox(...);
    ...
}

By wrapping messageboxes in non-asynchronous service calls and mocking them, for longer scenarios you'll start to contradict "Arrange-Act-Assert" pattern by predicting user action before it actually happens (doing "Arrange" instead of "Act"), which can cause numerous problems in testing, especially if your tests are done using BDD/SpecFlow. Making these calls asynchronous allows to avoid such problems. See my blog article for details and samples of larger-scale tests with messageboxes.