How to test file system operations

Question

I have a method which synchronizes two folders, that looks like this:

void Synchronize(string folderAPath, string folderBPath)
{
    //Code to synchronize the folders
}

What would be the best way to test if the files were synchronized properly, or in general, test methods that manipulate the file system? Is there a way to set up virtual folders?

Answer 1

As @BrokenGlass already advised, hiding the actual API behind a mockable interface allows you to unit test your logic. I would do this only though if there is substantial logic in there to justify the extra complexity needed to make the interface unit testable. Testing that the code really works under real circumstances, on the real filesystem needs integration tests anyway, so in simple cases the unit tests could be skipped, to use one's limited resources more effectively.