We should consider updating the timeout error message from "timeout of [time] exceeded. Ensure the done() callback is being called in this test." to something like "timeout of [time] exceeded. Ensure the test completes within [time] or increase the timeout set, and ensure the done() callback is being called when this test completes." The current message makes it sound like the problem is forgetting to call done even when the problem is simply that the test took too long or that some asynchronous action never got called back.