Unit Test Versus Initration Test?

i like a behavior over implementation, and that kind of falls into what intigration tests. So wut. How do i define uni test versus int migration tests? I tried to do like martin and define it as, for a while i used to define a unit tests as anything a developer would write. But really as a functionality, a unit of functionality. You don't stub it or mock it, but you just assume everything else is correct.