Hmm, I don't know if testing every zone is necessary. However, I would not be comfortable picking out the zones one ought to test, considering:

         if ('Riyadh8' in self.zonename or
            # From tzdata NEWS file:
            # The files solar87, solar88, and solar89 are no longer distributed.
            # They were a negative experiment - that is, a demonstration that
            # tz data can represent solar time only with some difficulty and error.
            # Their presence in the distribution caused confusion, as Riyadh
            # civil time was generally not solar time in those years.
self.zonename.startswith('right/')):

and:

> # Iran had a sub-minute UTC offset before 1946.

in https://github.com/python/cpython/blob/master/Lib/test/datetimetester.py#L4865

Perhaps @belopolsky can suggest something? (Already in Nosy List).

~
ut