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Documentation-Driven Development (DDD)

Documentation-Driven Development

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.
  • Documentation and software should both be versioned, and versions should match, so someone working with old versions of software should be able to find the proper documentation.

So, the preferred order of operations for new features:

  • Write documentation
  • Get feedback on documentation
  • Test-driven development (where tests align with documentation)
  • Push features to staging
  • Functional testing on staging, as necessary
  • Deliver feature
  • Publish documentation
  • Increment versions
@WarrenWongCodes
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Absolutely agree with this sentiment. I find a lot of places find documentation as a chore. And then when newer developers try to figure out the why and design behind why certain features work they way they do are confused and ask if there is any documentation.

And the response is usually some tribal knowledge passed through multiple devs or not really sure, its always been like this.

@dschiavu
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@WarrenWongCodes Indeed. Also, I think of Documentation-driven Development and Readme-driven Development as almost variants of Knuth's Literate Programming.

@jons
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jons commented Feb 16, 2023

in that case, i propose Artificially Literate Programming -- tongue planted firmly in cheek -- wherein the discipline is precisely as Knuth described it, but one uses GPT models to assist the process.

@ShalokShalom
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@hinell
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hinell commented Nov 14, 2023

Document a concept before implementing it. If you take a break from development, you can always go back and refresh your memory by reading docs. Tests are secondary.

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