Dev: Code Testing

Automated unit testing is an essential part of a reliable software package. In unit testing, you set the environment to a particular state, run some code in your software, and verify that the resulting environment is what you were expecting.

1) Any functionality you commit should have corresponding test cases that cover 100% of the lines of that code and does sanity-checks on its results.

2) Write doctests to illustrate the basics of your functionality.

3) When writing Django-powered stuff, test the views as well as other stuff.
http://docs.djangoproject.com/en/dev/topics/testing/

Test-driven Development [TDD] is a paradigm whereby you write the tests for application functionality before writing the functionality itself. It's a much better idea than simply writing the tests in one huge batch at the end, and saves you tearing your hair out.