Chain Gang
A couple of tests that must run in a certain order, i.e. one test changes the global state of the system (global variables, data in the database) and the next test(s) depends on it.
You often see this in database tests. Instead of doing a rollback in teardown(), tests commit their changes to the database. Another common cause is that changes to the global state aren't wrapped in try/finally blocks which clean up should the test fail.
