What I do for graphics (never had to test audio programs) is to make the actual graphics code as simple as possible - no logic, very few lines: just take this t

What I do for graphics (never had to test audio programs) is to make the actual graphics code as simple as possible - no logic, very few lines: just take this thing and put it on screen. This way, I can inspect it visually, test it manually once and be reasonably certain that it will work. (Which can be incorrect, of course, but it's relatively rare. Lost a contract because of it once, so it can also be painful :D) Put all the logic in a class that can be tested and that returns something that can be used in the "get this, put it on screen" part mentioned above.