Add some more unit tests and validation code for the StockItem model

- Ensure that the build part matches the stockitem part!

InvenTree/stock/models.py

@@ -275,11 +275,25 @@ class StockItem(MPTTModel):
             # TODO - Find a test than can be perfomed...
             pass
 
+        # Ensure that the item cannot be assigned to itself
         if self.belongs_to and self.belongs_to.pk == self.pk:
             raise ValidationError({
                 'belongs_to': _('Item cannot belong to itself')
             })
 
+        # If the item is marked as "is_building", it must point to a build!
+        if self.is_building and not self.build:
+            raise ValidationError({
+                'build': _("Item must have a build reference if is_building=True")
+            })
+
+        # If the item points to a build, check that the Part references match
+        if self.build:
+            if not self.part == self.build.part:
+                raise ValidationError({
+                    'build': _("Build reference does not point to the same part object")
+                })
+
     def get_absolute_url(self):
         return reverse('stock-item-detail', kwargs={'pk': self.id})
 

InvenTree/stock/tests.py

@@ -7,7 +7,9 @@ import datetime
 
 from .models import StockLocation, StockItem, StockItemTracking
 from .models import StockItemTestResult
+
 from part.models import Part
+from build.models import Build
 
 
 class StockTest(TestCase):
@@ -62,9 +64,14 @@ class StockTest(TestCase):
         # And there should be *no* items being build
         self.assertEqual(part.quantity_being_built, 0)
 
+        build = Build.objects.create(part=part, title='A test build', quantity=1)
+
         # Add some stock items which are "building"
         for i in range(10):
-            StockItem.objects.create(part=part, quantity=10, is_building=True)
+            StockItem.objects.create(
+                part=part, build=build,
+                quantity=10, is_building=True
+            )
 
         # The "is_building" quantity should not be counted here
         self.assertEqual(part.total_stock, n + 5)