Made minor changes, trying to get regression test to work. Still not sure what is wrong. Velocity must be updating by the wrong amount but it's not obvious which section is giving an error since it all runs.
Reverted fixture.yml back to it's original form in case the data is being process incorrect from here.
Changed test_boids.py but the regression test countinues to fail.
The problem with the regression tests discovered! match_speed was defined the wrong way round, adding velocity in the wrong direction!
Seperated update_boids.py from boids.py so that when test_boids used update_boids it didn't run all of boids. Not only that, I also changed the way the loops over the match_speed method work since this also meant the regression test failed.
Changed boids.py so it imports update_boids from update_boids.py.
Made the regression test check the y position and both the velocities also.