In this chapter, we will discuss the following topics:
- Test-driven development
- Dos and don'ts of writing tests
- Mocking
- Debugging
- Logging
Every programmer must have, at least, considered skipping writing tests. In Django, the default app layout has a tests.py module with some placeholder content. It is a reminder that tests are needed. However, we are often tempted to skip it.
In Django, writing tests is quite similar to writing code. In fact, it is practically code. So, the process of writing tests might seem like doubling (or even more) the effort of coding. Sometimes, we are under so much time pressure that it might seem ridiculous to spend time writing tests when we are just trying to make things work.
However, eventually, it is pointless to skip tests if you ever want anyone else to use your code. Imagine that you invented an electric razor and tried to sell it to your friend saying that it worked well for you, but you haven't tested it properly. Being a good friend of yours he or she might agree, but imagine the horror if you told this to a stranger.
Tests in a software check whether it works as expected. Without tests, you might be able to say that your code works, but you will have no way to prove that it works correctly.
Additionally, it is important to remember that it can be dangerous to omit unit testing in Python because of its duck-typing nature. Unlike languages such as Haskell, type checking cannot be strictly enforced at compile time. Unit tests, being run at runtime (although in a separate execution), are essential in Python development.
Writing tests can be a humbling experience. The tests will point out your mistakes and you will get a chance to make an early course correction. In fact, there are some who advocate writing tests before the code itself.