During July 2025, Merlin Unterfinger developed an integration test for the matsim-org/matsim-libs repository, focusing on the Railsim module’s complex 3-way junction scenarios. He introduced the microJunctionFlat test, which simulates bidirectional rail traffic, conflicting paths, dense schedules, and short headways to rigorously validate conflict resolution and resource locking mechanisms. Using Java and leveraging his expertise in integration testing and rail simulation, Merlin’s work established a repeatable framework for high-contention scenario validation. This targeted approach expanded test coverage for critical Railsim pathways, enabling earlier regression detection and improving reliability for future development and deployment within the MATSim ecosystem.