Don't stop test runs at midnight.

Without this, the generator will stop at midnight as the testrun window jumps
into the next day. By checking if the current time falls in yesterday's window
we take care of this anomaly.

victronenergy/venus#279

startstop.py

@@ -576,13 +576,28 @@ def _evaluate_testrun_condition(self):
 			return False
 
 		today = datetime.date.today()
+		yesterday = today - datetime.timedelta(days=1) # Should deal well with DST
+		now = time.time()
 		runtillbatteryfull = self._settings['testruntillbatteryfull'] == 1
 		soc = self._get_updated_values()['soc']
 		batteryisfull = runtillbatteryfull and soc == 100
+		duration = 60 if runtillbatteryfull else self._settings['testrunruntime']
 
 		try:
 			startdate = datetime.date.fromtimestamp(self._settings['testrunstartdate'])
-			starttime = time.mktime(today.timetuple()) + self._settings['testrunstarttimer']
+			_starttime = time.mktime(yesterday.timetuple()) + self._settings['testrunstarttimer']
+
+			# today might in fact still be yesterday, if this test run started
+			# before midnight and finishes after. If `now` still falls in
+			# yesterday's window, then by the temporal anthropic principle,
+			# which I just made up but loosely states that time must have
+			# these properties for observers to exist, it must be yesterday
+			# because we are here to observe it.
+			if _starttime <= now <= _starttime + duration:
+				today = yesterday
+				starttime = _starttime
+			else:
+				starttime = time.mktime(today.timetuple()) + self._settings['testrunstarttimer']
 		except ValueError:
 			logging.debug('Invalid dates, skipping testrun')
 			return False
@@ -600,11 +615,11 @@ def _evaluate_testrun_condition(self):
 		self._dbusservice['/SkipTestRun'] = int(not needed)
 
 		interval = self._settings['testruninterval']
-		stoptime = (starttime + self._settings['testrunruntime']) if not runtillbatteryfull else (starttime + 60)
+		stoptime = starttime + duration
 		elapseddays = (today - startdate).days
 		mod = elapseddays % interval
 
-		start = (not bool(mod) and (time.time() >= starttime) and (time.time() <= stoptime))
+		start = not bool(mod) and starttime <= now <= stoptime
 
 		if runtillbatteryfull:
 			if soc is not None:
@@ -622,7 +637,7 @@ def _evaluate_testrun_condition(self):
 			else:
 				start = False
 
-		if not bool(mod) and (time.time() <= stoptime):
+		if not bool(mod) and (now <= stoptime):
 			self._dbusservice['/NextTestRun'] = starttime
 		else:
 			self._dbusservice['/NextTestRun'] = (time.mktime((today + datetime.timedelta(days=interval - mod)).timetuple()) +