Writing unit tests

Information on writing unit tests, from the Internet:

General Guidance

• When you write a function, immediately write the test. (Or, better, write the test before you write the function).
• If function A creates a data object and then calls function B, which does something to the data object and then calls function C, it may be difficult to generate a test for each function. This may indicate that you should refactor your program. For example, you may wish to create a new class, AA, which has different methods for different data functions. You can then write tests for each of these methods.

Testing Python with py.test

• Use pytest for Python unit tests. It's the best developed test framework, and widely supported.
• Introduction to pytest, by Brian Okken, who wrote the book "Python Testing with pytest"
• 2005 article on Python unit testing with py.test

Other collateral

• Excellent article on Toptal about writing unit tests,