Overdue order notification (#3114)

* Adds a background task to notify users when a PurchaseOrder becomes overdue

* Schedule the overdue purchaseorder check to occur daily

* Allow notifications to be sent to "Owner" instances

- Extract user information from the Owner instance

* add unit test to ensure notifications are sent for overdue purchase orders

* Adds notification for overdue sales orders

* Clean up notification display panel

- Simplify rendering
- Order "newest at top"
- Element alignment tweaks

* style fixes

* More style fixes

* Tweak notification padding

* Fix import order

* Adds task to notify user of overdue build orders

* Adds unit tests for build order notifications

* Refactor subject line for emails:

- Use the configured instance title as a prefix for the subject line

* Add email template for overdue build orders

* Fix unit tests to accommodate new default value

* Logic error fix

InvenTree/build/test_build.py

@@ -1,11 +1,16 @@
 """Unit tests for the 'build' models"""
 
+from datetime import datetime, timedelta
+
 from django.test import TestCase
 
+from django.contrib.auth import get_user_model
 from django.core.exceptions import ValidationError
 
 from InvenTree import status_codes as status
 
+import common.models
+import build.tasks
 from build.models import Build, BuildItem, get_next_build_number
 from part.models import Part, BomItem, BomItemSubstitute
 from stock.models import StockItem
@@ -14,6 +19,10 @@ from stock.models import StockItem
 class BuildTestBase(TestCase):
     """Run some tests to ensure that the Build model is working properly."""
 
+    fixtures = [
+        'users',
+    ]
+
     def setUp(self):
         """Initialize data to use for these tests.
 
@@ -84,7 +93,8 @@ class BuildTestBase(TestCase):
             reference=ref,
             title="This is a build",
             part=self.assembly,
-            quantity=10
+            quantity=10,
+            issued_by=get_user_model().objects.get(pk=1),
         )
 
         # Create some build output (StockItem) objects
@@ -450,8 +460,6 @@ class AutoAllocationTests(BuildTestBase):
             substitutes=True,
         )
 
-        # self.assertTrue(self.build.are_untracked_parts_allocated())
-
         # self.assertEqual(self.build.allocated_stock.count(), 8)
         self.assertEqual(self.build.unallocated_quantity(self.bom_item_1), 0)
         self.assertEqual(self.build.unallocated_quantity(self.bom_item_2), 0)
@@ -471,3 +479,19 @@ class AutoAllocationTests(BuildTestBase):
 
         self.assertEqual(self.build.unallocated_quantity(self.bom_item_1), 0)
         self.assertEqual(self.build.unallocated_quantity(self.bom_item_2), 0)
+
+    def test_overdue_notification(self):
+        """Test sending of notifications when a build order is overdue."""
+
+        self.build.target_date = datetime.now().date() - timedelta(days=1)
+        self.build.save()
+
+        # Check for overdue orders
+        build.tasks.check_overdue_build_orders()
+
+        message = common.models.NotificationMessage.objects.get(
+            category='build.overdue_build_order',
+            user__id=1,
+        )
+
+        self.assertEqual(message.name, 'Overdue Build Order')