Fix wrong time zone handling in telemetry

doc/dev/telemetry.rst

@@ -276,7 +276,7 @@ scanning goes to :data:`enhydris.telemetry.drivers`.
       format`_.
 
       ``enhydris_timeseries_end_date`` is either None (meaning get all
-      measurements since the beginning) or a datetime.
+      measurements since the beginning) or an aware datetime.
 
       In order to avoid loading the server too much, this should not
       return more than a reasonable number of records, such as half a

enhydris/telemetry/models.py

@@ -46,13 +46,8 @@ class Telemetry(models.Model):
         max_length=35,
         blank=True,
         choices=timezone_choices,
-        verbose_name=_("Time zone of the timestamps (useful only for DST switches)"),
-        help_text=_(
-            "If the station switches to Daylight Saving Time, enter the time zone "
-            "here. This is only used in order to know when the DST switches occur. "
-            "The timestamp, after converting to winter time, is entered as is. If "
-            "the station does not switch to DST, leave this field empty."
-        ),
+        verbose_name=_("Time zone of the timestamps"),
+        help_text=_('The time zone of the data, like "Europe/Athens" or "Etc/GMT".'),
     )
     fetch_interval_minutes = models.PositiveSmallIntegerField(
         validators=[MinValueValidator(10), MaxValueValidator(1440)],
@@ -108,8 +103,6 @@ def _fetch_sensor(self, sensor):
             timeseries_group_id=sensor.timeseries_group_id, type=Timeseries.INITIAL
         )
         timeseries_end_date = timeseries.end_date
-        if timeseries_end_date is not None:
-            timeseries_end_date = timeseries_end_date.replace(tzinfo=None)
         measurements = self.api_client.get_measurements(
             sensor_id=sensor.sensor_id, timeseries_end_date=timeseries_end_date
         )

enhydris/telemetry/tests/test_models.py

@@ -227,63 +227,6 @@ def test_appends_data_to_database(self):
         self.assertEqual(data.getvalue().strip(), "1990-01-01 00:00,42.0,")
 
 
-class TelemetryFetchIgnoresTimeZoneTestCase(TelemetryFetchTestCaseBase):
-    """Test that timeseries_end_date is always naive
-
-    When records already exist in the timeseries before calling fetch(), the
-    timeseries_end_date specified in get_measurement() is determined from the
-    latest of these records. However, storage of timestamps in the database is
-    always aware, so we need to convert it to naive before calling
-    get_measurement(). This TestCases checks that this is done.
-
-    Unfortunately, at the time of this writing, if this test fails, the error
-    message is not easy to understand, because fetch() catches all exceptions and
-    records them in the TelemetryLog.  So while debugging things related to this
-    test it's a good idea to temporarily modify fetch() to raise exceptions.
-    """
-
-    def setUp(self):
-        timeseries = Timeseries(
-            timeseries_group_id=self.timeseries_group.id, type=Timeseries.INITIAL
-        )
-        timeseries.save()
-        timeseries.append_data(
-            StringIO("2022-06-14 08:00,42.1,\n"), default_timezone="Etc/GMT-2"
-        )
-
-    @patch("enhydris.telemetry.types.meteoview2.requests.request")
-    def test_ignores_timezone(self, mock_request):
-        self._set_mock_request_return_values(mock_request)
-        self.telemetry.fetch()
-        self.assertEqual(
-            mock_request.call_args.kwargs,
-            {
-                "headers": {
-                    "content-type": "application/json",
-                    "Authorization": "Bearer topsecretapitoken",
-                },
-                "data": json.dumps(
-                    {
-                        "sensor": ["257"],
-                        "datefrom": "2022-06-14",
-                        "timefrom": "08:01",
-                        "dateto": "2022-12-11",
-                    }
-                ),
-            },
-        )
-
-    def _set_mock_request_return_values(self, mock_request):
-        mock_request.side_effect = [
-            MagicMock(  # Response for login
-                **{"json.return_value": {"code": "200", "token": "topsecretapitoken"}}
-            ),
-            MagicMock(  # Response for measurements
-                **{"json.return_value": "irrelevant"}
-            ),
-        ]
-
-
 @patch("enhydris.telemetry.types.meteoview2.requests.request")
 class TelemetryFetchDealsWithTooCloseTimestampsTestCase(TelemetryFetchTestCaseBase):
     """Test successive timestamps less than one minute apart

enhydris/telemetry/tests/test_types/test_meteoview2.py

@@ -1,13 +1,16 @@
 import datetime as dt
 import json
+from io import StringIO
 from unittest import TestCase
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 from freezegun import freeze_time
 from requests import Timeout
 
+from enhydris.models import Timeseries
 from enhydris.telemetry import TelemetryError
 from enhydris.telemetry.models import Telemetry
+from enhydris.telemetry.tests.test_models import TelemetryFetchTestCaseBase
 from enhydris.telemetry.types.meteoview2 import TelemetryAPIClient
 
 
@@ -143,6 +146,64 @@ def _set_successful_request_result(self, mock_request):
         }
 
 
+class TelemetryFetchIgnoresTimeZoneTestCase(TelemetryFetchTestCaseBase):
+    """Test that timeseries_end_date is always naive
+
+    When records already exist in the timeseries before calling fetch(), the
+    timeseries_end_date specified in get_measurements() is determined from the
+    latest of these records. meteoview2 converts the timeseries_end_date to naive.
+    This TestCase checks that this is done.
+
+    Unfortunately, at the time of this writing, if this test fails, the error
+    message is not easy to understand, because fetch() catches all exceptions and
+    records them in the TelemetryLog.  So while debugging things related to this
+    test it's a good idea to temporarily modify fetch() to raise exceptions.
+    """
+
+    def setUp(self):
+        timeseries = Timeseries(
+            timeseries_group_id=self.timeseries_group.id,
+            type=Timeseries.INITIAL,
+        )
+        timeseries.save()
+        timeseries.append_data(
+            StringIO("2022-06-14 08:00,42.1,\n"), default_timezone="Etc/GMT"
+        )
+        self.telemetry.data_timezone = "Etc/GMT-2"
+
+    @patch("enhydris.telemetry.types.meteoview2.requests.request")
+    def test_ignores_timezone(self, mock_request):
+        self._set_mock_request_return_values(mock_request)
+        self.telemetry.fetch()
+        self.assertEqual(
+            mock_request.call_args.kwargs,
+            {
+                "headers": {
+                    "content-type": "application/json",
+                    "Authorization": "Bearer topsecretapitoken",
+                },
+                "data": json.dumps(
+                    {
+                        "sensor": ["257"],
+                        "datefrom": "2022-06-14",
+                        "timefrom": "10:01",
+                        "dateto": "2022-12-11",
+                    }
+                ),
+            },
+        )
+
+    def _set_mock_request_return_values(self, mock_request):
+        mock_request.side_effect = [
+            MagicMock(  # Response for login
+                **{"json.return_value": {"code": "200", "token": "topsecretapitoken"}}
+            ),
+            MagicMock(  # Response for measurements
+                **{"json.return_value": "irrelevant"}
+            ),
+        ]
+
+
 @patch("enhydris.telemetry.types.meteoview2.requests.request")
 @freeze_time("2022-06-14 08:35")
 class GetMeasurementsTestCase(LoggedOnTestCaseBase):

enhydris/telemetry/types/meteoview2.py

@@ -80,6 +80,7 @@ def get_measurements(self, sensor_id, timeseries_end_date):
 
     def _get_start_date(self, sensor_id, timeseries_end_date):
         if timeseries_end_date is not None:
+            timeseries_end_date = timeseries_end_date.replace(tzinfo=None)
             start_date = timeseries_end_date + dt.timedelta(minutes=1)
         else:
             start_date = dt.datetime(1990, 1, 1)