Fix DST related errors, check for timezone support. Edit tox file.

[skip ci]

Author: Smart-Dev00214

mssql/features.py

@@ -19,7 +19,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     has_select_for_update = True
     has_select_for_update_nowait = True
     has_select_for_update_skip_locked = True
-    has_zoneinfo_database = False
     ignores_table_name_case = True
     ignores_quoted_identifier_case = True
     requires_literal_defaults = True
@@ -56,3 +55,9 @@ def supports_partial_indexes(self):
     @cached_property
     def supports_functions_in_partial_indexes(self):
         return self.connection.sql_server_version > 2005
+
+    @cached_property
+    def has_zoneinfo_database(self):
+        with self.connection.cursor() as cursor:
+            cursor.execute("SELECT TOP 1 1 FROM sys.time_zone_info")
+            return cursor.fetchone() is not None

mssql/operations.py

@@ -34,7 +34,7 @@ def _get_utcoffset(self, tzname):
         # no way to take DST into account at this point
         now = datetime.datetime.now()
         delta = zone.localize(now, is_dst=False).utcoffset()
-        return delta.days * 86400 + delta.seconds
+        return delta.days * 86400 + delta.seconds - zone.dst(now).seconds
 
     def bulk_batch_size(self, fields, objs):
         """

test.sh

@@ -12,7 +12,7 @@ git fetch --depth=1 origin +refs/tags/*:refs/tags/*
 git checkout $DJANGO_VERSION
 pip install -r tests/requirements/py3.txt
 
-python tests/runtests.py --settings=testapp.settings --noinput --keepdb \
+python tests/runtests.py --settings=testapp.settings --noinput \
     aggregation \
     aggregation_regress \
     annotations \

tox.ini

@@ -9,8 +9,7 @@ whitelist_externals =
     /bin/bash
 
 commands =
-    python manage.py test --keepdb
-    python manage.py install_regex_clr test_default
+    python manage.py test
     bash test.sh
 
 deps =