Testing

To ensure that your code is correct and doesn't break on future changes, writing tests is usually one of the best things you can do.

In Python, there are a few frameworks to implement test suites that can automatically verify code reliability, implement different patterns such as behavior-driver development (BDD), or even automatically find corner cases for you.

But simple automatic tests can be written just by relying on the standard library itself, so that you will need third-party testing frameworks only if you need specific plugins or patterns.

The standard library has the unittest module, which allows us to write tests for our software, run them, and report the state of the test suite.

How to do it...

For this recipe, the following steps are to be performed:

1. Say we have a divide function we want to write tests for:

def divide(x, y):
    return x / y

2. We need to create a file named test_divide.py (it's important that files containing tests are named test_*.py or the tests won't run)....