"I have a confession. Even as the author of a public domain Python library in fairly wide use, I have been far less than systematic in including unit tests for my modules. In fact, the bulk of those tests that are included in Gnosis Utilities fall under gnosis.xml.pickle, and were written by a contributor to that subpackage. I have found that the large majority of third-party Python packages I download also lack a thorough unit test collection.
"Moreover, the tests that exist in Gnosis Utilities suffer from another flaw: you often need to understand the expected output in a fair amount of detail to even know whether a test succeeds or fails. What passes as tests are actually -- in many cases -- more like small utilities that utilize parts of the library. These tests (or utilities) allow input from arbitrary data sources (of the right type) and/or output in descriptive data formats. These test utilities are actually rather useful when you need to debug some subtle error. But as self-explanatory sanity checks of changes between library versions, these kinds of tests do not succeed.
"In this installment, I try to improve the tests in my utility collection using the Python standard library modules doctest and unittest, and I walk you through my experience (with a few pointers on best approaches)..."
