  Context: Agile development is in widespread use, even in safety-critical
domains. Motivation: However, there is a lack of an ap- propriate safety
analysis and verification method in agile development. Objective: In this
paper, we investigate the use of Behavior Driven De- velopment (BDD) instead of
standard User Acceptance Testing (UAT) for safety verification with
System-Theoretic Process Analysis (STPA) for safety analysis in agile
development. Method: We evaluate the effect of this combination in a controlled
experiment with 44 students in terms of productivity, test thoroughness, fault
detection effectiveness and com- munication effectiveness. Results: The results
show that BDD is more effective for safety verification regarding the impact on
communication effectiveness than standard UAT, whereas productivity, test
thorough- ness and fault detection effectiveness show no statistically
significant difference in our controlled experiment. Conclusion: The
combination of BDD and STPA seems promising with an enhancement on communica-
tion, but its impact needs more research.
