Test-Driven Development Benefits Beyond Design Quality: Flow State and Developer Experience

Test-driven development (TDD) is a coding technique that combines design and testing in an iterative and incremental fashion. It prescribes that tests written before the production code help the developer to find good interfaces and to evolve the design safely and incrementally. Improvements on the design of code produced by the test-driven development approach have been extensively evaluated in the literature; in this research, we focus on seeking explanations on the benefits of TDD in another dimension which we believe has been undervalued – developer experience. We identified that there is a natural connection between the TDD approach and flow state, a well-known mental state characterized by total immersion, focus, and involvement in a task that promotes increased enjoyment and productivity. We present evidence that the continuous stream of mini-scope, short-lived, red-green-refactor cycles of TDD frame the development task as a structure that creates the pre-conditions reported by neuroscience research to produce flow state, namely (1) clear goals, (2) unambiguous feedback, (3) challenge-skill balance and (4) sense of control. Our work contributes to increase the understanding on the reasons why adopting practices such as TDD can benefit the software development process as a whole and can support its adoption in software development projects.