You definitely should carry out unit tests for your apps. Whether you follow TDD strictly or not, they can be very useful, especially for regression tests. Most continuous integration tools out there fully support running unit tests. Just don't try to cover everything; focus on the critical parts of your app and, if time allows, then proceed to the other parts. It is unreasonable to think that we will have 100% coverage in most projects, so we need to make decisions. Mocking frameworks play an essential role here as they allow us to simulate third-party services nicely.
Automated integration tests, as we saw here, allow us to test features that aren't available in unit tests, and these cover other parts of our needs.
This chapter covered ways to test our apps, either part of them in isolation or the system as a whole. Unit tests are useful as they can ensure that our application still works the way it is supposed to, even though we are making...