Cleanup / consolidate unit testing code (#4831)

- Move testing code out of helpers.py
- Create new file unit_test.py

InvenTree/stock/test_api.py

@@ -16,8 +16,8 @@ from rest_framework import status
 import company.models
 import part.models
 from common.models import InvenTreeSetting
-from InvenTree.api_tester import InvenTreeAPITestCase
 from InvenTree.status_codes import StockStatus
+from InvenTree.unit_test import InvenTreeAPITestCase
 from part.models import Part
 from stock.models import StockItem, StockItemTestResult, StockLocation
 

InvenTree/stock/test_migrations.py

@@ -2,14 +2,14 @@
 
 from django_test_migrations.contrib.unittest_case import MigratorTestCase
 
-from InvenTree import helpers
+from InvenTree import unit_test
 
 
 class TestSerialNumberMigration(MigratorTestCase):
     """Test data migration which updates serial numbers"""
 
     migrate_from = ('stock', '0067_alter_stockitem_part')
-    migrate_to = ('stock', helpers.getNewestMigrationFile('stock'))
+    migrate_to = ('stock', unit_test.getNewestMigrationFile('stock'))
 
     def prepare(self):
         """Create initial data for this migration"""
@@ -73,7 +73,7 @@ class TestScheduledForDeletionMigration(MigratorTestCase):
     """Test data migration for removing 'scheduled_for_deletion' field"""
 
     migrate_from = ('stock', '0066_stockitem_scheduled_for_deletion')
-    migrate_to = ('stock', helpers.getNewestMigrationFile('stock'))
+    migrate_to = ('stock', unit_test.getNewestMigrationFile('stock'))
 
     def prepare(self):
         """Create some initial stock items"""

InvenTree/stock/test_views.py

@@ -4,8 +4,8 @@ from django.contrib.auth.models import Group
 from django.urls import reverse
 
 from common.models import InvenTreeSetting
-from InvenTree.helpers import InvenTreeTestCase
 from InvenTree.status_codes import StockStatus
+from InvenTree.unit_test import InvenTreeTestCase
 from stock.models import StockItem, StockLocation
 from users.models import Owner
 

InvenTree/stock/tests.py

@@ -9,8 +9,8 @@ from django.test import override_settings
 from build.models import Build
 from common.models import InvenTreeSetting
 from company.models import Company
-from InvenTree.helpers import InvenTreeTestCase
 from InvenTree.status_codes import StockHistoryCode
+from InvenTree.unit_test import InvenTreeTestCase
 from order.models import SalesOrder
 from part.models import Part