We study whether and in which phase Test-Driven Development (TDD) influences affective states of novice developers in terms of pleasure, arousal, dominance, and liking. We performed a controlled experiment with 29 novice developers. Developers in the treatment group performed a development task using TDD, whereas those in the control group used a non-TDD development approach. We compared the affective reactions to the development approaches, as well as to the implementation and testing phases, exploiting a lightweight, powerful, and widely used tool, i.e., Self-Assessment Manikin. We observed that there is a difference between the two development approaches in terms of affective reactions. Therefore, it seems that affective reactions play an important role when applying TDD and their investigation could help researchers to better understand such a development approach
