Tests will save you time
Tests don’t just identify problems, they prevent them
Tests make your code more attractive
You might have created a brilliant piece of software, but you will find that many other developers will simply refuse to look at it because it lacks tests; without tests, they won’t trust it. Jacob Kaplan-Moss, one of Django’s original developers, says “Code without tests is broken by design.”
Tests help teams work together
The previous points are written from the point of view of a single developer maintaining an application. Complex applications will be maintained by teams. Tests guarantee that colleagues don’t inadvertently break your code (and that you don’t break theirs without knowing).
When testing, more is better
It might seem that our tests are growing out of control. It doesn’t matter. Let them grow. For the most part, you can write a test once and then forget about it. It will continue performing its useful function as you continue to develop your program.
At worst, as you continue developing, you might find that you have some tests that are now redundant. Even that’s not a problem; in testing redundancy is a good thing.
As long as your tests are sensibly arranged, they won’t become unmanageable. Good rules-of-thumb include having:
- a separate TestClass for each model or view
- a separate test method for each set of conditions you want to test
- test method names that describe their function
