How do teams of programmers continuously write and revise code without breaking things? Unit tests define a function's expected behavior and then enforce that those requirements are met.

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TIMESTAMPS:
00:00 - 00:23 : programming teams
00:24 - 00:58 : what is a unit test?
00:59 - 01:36 : test automation
01:37 - 02:13 : code coverage
02:14 - 02:58 : choosing test cases
02:59 - 04:02 : unittest module syntax
04:03 - 04:44 : practical advice for beginners