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Test-Driven Development with Python, 3rd Edition
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Test-Driven Development with Python, 3rd Edition

by Harry Percival
October 2025
Intermediate to advanced
712 pages
14h 24m
English
O'Reilly Media, Inc.
Content preview from Test-Driven Development with Python, 3rd Edition

Chapter 14. Validation at the Database Layer

Over the next few chapters, we’ll talk about testing and implementing validation of user inputs.

In terms of content, there’s going to be quite a lot of material here that’s more about the specifics of Django, and less discussion of TDD philosophy. That doesn’t mean you won’t be learning anything about testing—​there are plenty of little testing tidbits in here, but perhaps it’s more about really getting into the swing of things, the rhythm of TDD, and how we get work done.

Once we get through these three short chapters, I’ve saved a bit of fun with JavaScript (!) for the end of Part II. Then it’s on to Part III, where I promise we’ll get right back into some of the real nitty-gritty discussions on TDD methodology—​unit tests versus integration tests, mocking, and more. Stay tuned!

But for now, a little validation. Let’s just remind ourselves where our FT is pointing us:

$ python3 src/manage.py test functional_tests.test_list_item_validation [...] ====================================================================== ERROR: test_cannot_add_empty_list_items (functional_tests.test_list_item_valida tion.ItemValidationTest.test_cannot_add_empty_list_items) --------------------------------------------------------------------- Traceback (most recent call last): File "...goat-book/src/functional_tests/test_list_item_validation.py", line 16, in test_cannot_add_empty_list_items self.wait_for( ~~~~~~~~~~~~~^ lambda: self.assertEqual( ^^^^^^^^^^^^^^^^^^^^^^^^^ ...
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ISBN: 9781098148706Errata Page