Python Testing with pytest

Testing Plugins with pytester

Plugins are code that needs to be tested just like any other code. However, testing a change to a testing tool is a little tricky. When we tested the plugin manually with test_slow.py, we

• ran with -v to make sure the slow marked test was skipped,
• ran with -v --slow to make sure both tests ran, and
• ran with -v -m slow --slow to make sure just the slow test ran.

We’re going to automate those tests with the help of a plugin called pytester. pytester ships with pytest but is disabled by default. The first thing we need to do then, is to enable it in conftest.py:

ch15/pytest_skip_slow_final/tests/conftest.py

pytest_plugins = ["pytester"]

Now we can use pytester to write our test cases. pytester creates a temporary directory ...