Function test_date2num_dst

lib/matplotlib/tests/test_dates.py:991–1053

()

def test_date2num_dst():
    # Test for github issue #3896, but in date2num around DST transitions
    # with a timezone-aware pandas date_range object.

    class dt_tzaware(datetime.datetime):
        """
        This bug specifically occurs because of the normalization behavior of
        pandas Timestamp objects, so in order to replicate it, we need a
        datetime-like object that applies timezone normalization after
        subtraction.
        """

        def __sub__(self, other):
            r = super().__sub__(other)
            tzinfo = getattr(r, 'tzinfo', None)

            if tzinfo is not None:
                localizer = getattr(tzinfo, 'normalize', None)
                if localizer is not None:
                    r = tzinfo.normalize(r)

            if isinstance(r, datetime.datetime):
                r = self.mk_tzaware(r)

            return r

        def __add__(self, other):
            return self.mk_tzaware(super().__add__(other))

        def astimezone(self, tzinfo):
            dt = super().astimezone(tzinfo)
            return self.mk_tzaware(dt)

        @classmethod
        def mk_tzaware(cls, datetime_obj):
            kwargs = {}
            attrs = ('year',
                     'month',
                     'day',
                     'hour',
                     'minute',
                     'second',
                     'microsecond',
                     'tzinfo')

            for attr in attrs:
                val = getattr(datetime_obj, attr, None)
                if val is not None:
                    kwargs[attr] = val

            return cls(**kwargs)

    # Define a date_range function similar to pandas.date_range
    def date_range(start, freq, periods):
        dtstart = dt_tzaware.mk_tzaware(start)

        return [dtstart + (i * freq) for i in range(periods)]