DDT is not TDD

November 2019

I've worked with more than one team where we claimed to practice test-driven-development.

We would go on to write code, get it working, and then test what seems test-worthy.

Or worse we'd ship with no/minimal coverage and then add tests to critical and/or failing paths as they arose.

This is development-driven-testing, not test-driven-development.

Test-driven development involves building software in three steps (commonly summarised as red, green, refactor):

It's easy to assume that TDD is just a way to ensure full test coverage, but it provides much more additional value as a tool to reason about the problem at hand.

Evaluate whether you're practicing DDT or TDD, it may be time to swap those letters around.

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