Fix user requested timezones with mixed offsets

src/pywaterinfo/waterinfo.py

@@ -631,7 +631,9 @@ def get_timeseries_values(
                     df[key_name] = section[key_name]
             # convert datetime objects to Pandas timestamp
             if "Timestamp" in df.columns:
-                df["Timestamp"] = pd.to_datetime(df["Timestamp"])
+                # round trip via UTC to handle mixed time series
+                df["Timestamp"] = pd.to_datetime(
+                    df["Timestamp"], utc=True).dt.tz_convert(timezone)
             time_series.append(df)
 
         return pd.concat(time_series)

tests/test_waterinfo.py

@@ -353,10 +353,23 @@ def test_overwrite_timezone(self, connection, request):
             end="20190501 14:10",
             timezone="CET",
         )
-        assert is_datetime64tz_dtype(df["Timestamp"])
-        assert df["Timestamp"].dt.tz == datetime.timezone(
-            datetime.timedelta(seconds=7200)
-        )
+        assert isinstance(df["Timestamp"].dtype, pd.DatetimeTZDtype)
+        assert df["Timestamp"].dt.tz == pytz.timezone("CET")
+
+    def test_timezone_mixed_timezone(self, connection, request):
+        """Queries resulting in mixed timezone offsets are handled without warning
+
+        See also https://github.com/fluves/pywaterinfo/issues/67
+        """
+        connection = request.getfixturevalue(connection)
+        df = connection.get_timeseries_values('69928042',
+                                              start='2013-03-21 00:00:00',
+                                              end='2013-04-01 23:00:00',
+                                              timezone='CET',
+                                              returnfields="Timestamp,Value"
+                                              )
+        assert isinstance(df["Timestamp"].dtype, pd.DatetimeTZDtype)
+        assert df["Timestamp"].dt.tz == pytz.timezone("CET")
 
     def test_start_end_timezone(self, connection, request):
         """pywaterinfo can handle start/end dates already containing tz info"""