The philosophy behind Documentation-Driven Development is a simple: from the perspective of a user, if a feature is not documented, then it doesn't exist, and if a feature is documented incorrectly, then it's broken.
- Document the feature first. Figure out how you're going to describe the feature to users; if it's not documented, it doesn't exist. Documentation is the best way to define a feature in a user's eyes.
- Whenever possible, documentation should be reviewed by users (community or Spark Elite) before any development begins.
- Once documentation has been written, development should commence, and test-driven development is preferred.
- Unit tests should be written that test the features as described by the documentation. If the functionality ever comes out of alignment with the documentation, tests should fail.
- When a feature is being modified, it should be modified documentation-first.
- When documentation is modified, so should be the tests.