In both unittest and pytest, when a test function hits a failing assert, the test stops and is marked as a failed test. 

What if you want to keep going, and check more things?

 There are a few ways. One of them is subtests.

Python's unittest introduced subtests in Python 3.4.

 pytest introduced support for subtests with changes in pytest 4.4 and a plugin, called pytest-subtests.
 Subtests are still not really used that much.

But really, what are they? When could you use them?

 And more importantly, what should you watch out for if you decide to use them?

That's what Paul Ganssle and I will be talking about today.

Special Guest: Paul Ganssle.

Links:

• Subtests in Python — Paul's article on subtests
• subtests in unittest - Python docs 
• pytest-subtests: plugin to support subtests in pytest
• pytest-check: A pytest plugin that allows multiple failures per test.