region collector never finishes if start_time after end_time (probably stuck in infinite loop)

[gerritholl]

When the end time for a granule is before the start time, the region collector is apparently supposed to do something clever, judging from this code block:

pytroll-collectors/pytroll_collectors/region_collector.py

Lines 84 to 91 in 7cb0d48

	if start_time > end_time:
	old_end_time = end_time
	end_date = start_time.date()
	if end_time.time() < start_time.time():
	end_date += timedelta(days=1)
	end_time = datetime.combine(end_date, end_time.time())
	LOG.debug('Adjusted end time from %s to %s.',
	old_end_time, end_time)

However, I've tried to write a unit test for this, see #77 or

https://github.com/gerritholl/pytroll-collectors/blob/1ad53748b5b2c267f6513a13a1cb5d6b23cfc50c/pytroll_collectors/tests/test_region_collector.py

where this unit test never finishes, apparently stuck in an infinite loop:

@unittest.mock.patch("pyorbital.tlefile.urlopen", new=_fakeopen)
def test_faulty_end_time(europe_collector, caplog):
    """Test adapting if end_time before start_time."""
    granule_metadata = {
        "platform_name": "Metop-C",
        "sensor": "avhrr",
        "start_time": datetime.datetime(2021, 4, 11, 0, 0),
        "end_time": datetime.datetime(2021, 4, 10, 23, 58)}
    with caplog.at_level(logging.DEBUG):
        europe_collector(granule_metadata)
    assert "Adjusted end time" in caplog.text

which I suspect to be either one of those two:

pytroll-collectors/pytroll_collectors/region_collector.py

Lines 170 to 187 in 7cb0d48

	while True:
	gr_time += self.granule_duration
	gr_pass = Pass(platform, gr_time,
	gr_time + self.granule_duration,
	instrument=self.sensor)
	if not gr_pass.area_coverage(self.region) > 0:
	break
	self.planned_granule_times.add(gr_time)
	gr_time = start_time
	while True:
	gr_time -= self.granule_duration
	gr_pass = Pass(platform, gr_time,
	gr_time + self.granule_duration,
	instrument=self.sensor)
	if not gr_pass.area_coverage(self.region) > 0:
	break
	self.planned_granule_times.add(gr_time)