Might be better for testing if there were less zeros in the reference data. Particularly, the hour, min, sec and nanosec are all zeros, making unit tests less reliable. Perhaps, time could be something like: 12:34:56.123456789.
Related, would be good if the sample rate/period was not always 1. Because the "negative means period" concept, a reference files with high sample rate (>> 1) and low sample rate (<< -1) would be really useful to catch parse errors.
From @crotwell: