Time for action - nailing down the specification with unit tests
A specification—even a testable specification written in doctest—is still home to a lot of ambiguities that can be ironed out with good unit tests. Add that to the fact that the specification doesn't maintain separation between different tests, and you can see that it's time for your project to gain some unit tests.
- Find some element of your project which is described in (or implied by) your specification
- Write a unit test that describes the behavior of that element when given correct input
- Write a unit test that describes the behavior of that element when given incorrect input
- Write unit tests that describe the behavior of the element at the boundaries between correct and incorrect ...