TrafficControl: Opposite Direction TDD Case (1)

One big stub in trafficControl is that it currently only allows trains to travel on tracks in the intended direction (position 0 up to the end).

To enable trains to move in reversed directions, I will follow the Test-Driven-Development method.

The first iteration is to test a train on a station with one leaving reversed track. The track leaves Simrishamn (start) and arrives to Gärsnäs (end). A train in Gärsnäs that shall go to Simrishamn should find the track and travel in reverse on it to Simrishamn.

In this video, the train was supposed to travel back from Gärsnäs to Simrishamn, but that didn't happen.

The issue is that the method findLeavingTrackIndexToStation only searches for connected tracks where the end station is matching target station. For reversed tracks, the start station will match the target station. No suitable track is found and the function returns UNDEFINED.

To fix the issue, the program will search for a leaving track in the reversed direction in case it doesn't find a track in the ordinary direction.

A corresponding test case has been added:

With this change, the program still fails. After leaving Gärsnäs, the train enters the track near Simrishamn and travels to Gärsnäs. I'll  solve that in the next blog post.