refactor: update coverage score in nox file and cleanup imports in te…

…st_operations (#638)

* refactor: update coverage score in nox file and cleanup imports in test_operations

* refactor: lint correction in test_operations

noxfile.py

@@ -87,7 +87,7 @@ def default(session):
         "--cov-append",
         "--cov-config=.coveragerc",
         "--cov-report=",
-        "--cov-fail-under=65",
+        "--cov-fail-under=80",
         os.path.join("tests", "unit"),
         *session.posargs,
     )
@@ -157,7 +157,7 @@ def cover(session):
     test runs (not system test runs), and then erases coverage data.
     """
     session.install("coverage", "pytest-cov")
-    session.run("coverage", "report", "--show-missing", "--fail-under=65")
+    session.run("coverage", "report", "--show-missing", "--fail-under=80")
 
     session.run("coverage", "erase")
 

tests/unit/django_spanner/test_operations.py

@@ -4,10 +4,15 @@
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd
 
-from django.db.utils import DatabaseError
+from base64 import b64encode
 from datetime import timedelta
-from tests.unit.django_spanner.simple_test import SpannerSimpleTestClass
 from decimal import Decimal
+from django.conf import settings
+from django.core.management.color import no_style
+from django.db.utils import DatabaseError
+from google.cloud.spanner_dbapi.types import DateStr
+from tests.unit.django_spanner.simple_test import SpannerSimpleTestClass
+import uuid
 
 
 class TestOperations(SpannerSimpleTestClass):
@@ -29,8 +34,6 @@ def test_bulk_batch_size(self):
         )
 
     def test_sql_flush(self):
-        from django.core.management.color import no_style
-
         self.assertEqual(
             self.db_operations.sql_flush(
                 style=no_style(), tables=["Table1", "Table2"]
@@ -39,15 +42,11 @@ def test_sql_flush(self):
         )
 
     def test_sql_flush_empty_table_list(self):
-        from django.core.management.color import no_style
-
         self.assertEqual(
             self.db_operations.sql_flush(style=no_style(), tables=[]), [],
         )
 
     def test_adapt_datefield_value(self):
-        from google.cloud.spanner_dbapi.types import DateStr
-
         self.assertIsInstance(
             self.db_operations.adapt_datefield_value("dummy_date"), DateStr,
         )
@@ -69,8 +68,6 @@ def test_adapt_decimalfield_value_none(self):
         )
 
     def test_convert_binaryfield_value(self):
-        from base64 import b64encode
-
         self.assertEqual(
             self.db_operations.convert_binaryfield_value(
                 value=b64encode(b"abc"), expression=None, connection=None
@@ -96,8 +93,6 @@ def test_adapt_timefield_value_none(self):
         )
 
     def test_convert_uuidfield_value(self):
-        import uuid
-
         uuid_obj = uuid.uuid4()
         self.assertEqual(
             self.db_operations.convert_uuidfield_value(
@@ -126,8 +121,6 @@ def test_date_extract_sql_lookup_type_dayofweek(self):
         )
 
     def test_datetime_extract_sql(self):
-        from django.conf import settings
-
         settings.USE_TZ = True
         self.assertEqual(
             self.db_operations.datetime_extract_sql(
@@ -137,8 +130,6 @@ def test_datetime_extract_sql(self):
         )
 
     def test_datetime_extract_sql_use_tz_false(self):
-        from django.conf import settings
-
         settings.USE_TZ = False
         self.assertEqual(
             self.db_operations.datetime_extract_sql(
@@ -167,17 +158,13 @@ def test_datetime_cast_date_sql(self):
         )
 
     def test_datetime_cast_time_sql(self):
-        from django.conf import settings
-
         settings.USE_TZ = True
         self.assertEqual(
             self.db_operations.datetime_cast_time_sql("dummy_field", "IST"),
             "TIMESTAMP(FORMAT_TIMESTAMP('%Y-%m-%d %R:%E9S %Z', dummy_field, 'IST'))",
         )
 
     def test_datetime_cast_time_sql_use_tz_false(self):
-        from django.conf import settings
-
         settings.USE_TZ = False
         self.assertEqual(
             self.db_operations.datetime_cast_time_sql("dummy_field", "IST"),