We really need to have *some* independent test of all these.  Every ERFA routine (apart from utilities) should have a corresponding `t_<func>(int *status)` routine in `erfa/src/t_erfa_c.c`.  This gives at least one test case that can be replicated and shows that this wrapper is giving the same answer as the raw ERFA C routine.  From there we rely on ERFA being correct.