> What you want to test is the interface of your module to the rest of the application and whether it satisfies the published contract, and preferably if it han

> What you want to test is the interface of your module to the rest of the application and whether it satisfies the published contract, and preferably if it handles weird cases correctly. I don't know what's a "module". If a module is a "small unit of code" (eg, a class), that's usually what you cover in your unit test.