Part stocktake (#4069)

* Remove stat context variables

* Revert "Remove stat context variables"

This reverts commit 0989c308d0.

* Allow longer timeout for image download tests

* Create PartStocktake model

Model for representing stocktake entries against any given part

* Admin interface support for new model

* Adds API endpoint for listing stocktake information

* Bump API version

* Enable filtering and ordering for API endpoint

* Add model to permission group

* Add UI hooks for displaying stocktake data for a particular part

* Fix encoded type for 'quantity' field

* Load stocktake table for part

* Add "stocktake" button

* Add "note" field for stocktake

* Add user information when performing stocktake

* First pass at UI elements for performing stocktake

* Add user information to stocktake table

* Auto-calculate quantity based on available stock items

* add stocktake data as tabular inline (admin)

* js linting

* Add indication that a stock item has not been updated recently

* Display last stocktake information on part page

* js style fix

* Test fix for ongoing CI issues

* Add configurable option for controlling default "delete_on_deplete" behaviour

* Add id values to cells

* Hide action buttons (at least for now)

* Adds refresh button to table

* Add API endpoint to delete or edit stocktake entries

* Adds unit test for API list endpoint

* javascript linting

* More unit testing

* Add Part API filter for stocktake

* Add 'last_stocktake' field to Part model

- Gets filled out automatically when a new PartStocktake instance is created

* Update part table to include last_stocktake date

* Add simple unit test

* Fix test

InvenTree/part/test_api.py

@@ -20,7 +20,7 @@ from InvenTree.status_codes import (BuildStatus, PurchaseOrderStatus,
                                     StockStatus)
 from part.models import (BomItem, BomItemSubstitute, Part, PartCategory,
                          PartCategoryParameterTemplate, PartParameterTemplate,
-                         PartRelated)
+                         PartRelated, PartStocktake)
 from stock.models import StockItem, StockLocation
 
 
@@ -2779,3 +2779,141 @@ class PartInternalPriceBreakTest(InvenTreeAPITestCase):
 
         with self.assertRaises(Part.DoesNotExist):
             p.refresh_from_db()
+
+
+class PartStocktakeTest(InvenTreeAPITestCase):
+    """Unit tests for the part stocktake functionality"""
+
+    superuser = False
+    is_staff = False
+
+    fixtures = [
+        'category',
+        'part',
+        'location',
+    ]
+
+    def test_list_endpoint(self):
+        """Test the list endpoint for the stocktake data"""
+
+        url = reverse('api-part-stocktake-list')
+
+        self.assignRole('part.view')
+
+        # Initially, no stocktake entries
+        response = self.get(url, expected_code=200)
+
+        self.assertEqual(len(response.data), 0)
+
+        total = 0
+
+        # Create some entries
+        for p in Part.objects.all():
+
+            for n in range(p.pk):
+                PartStocktake.objects.create(
+                    part=p,
+                    quantity=(n + 1) * 100,
+                )
+
+            total += p.pk
+
+            response = self.get(
+                url,
+                {
+                    'part': p.pk,
+                },
+                expected_code=200,
+            )
+
+            # List by part ID
+            self.assertEqual(len(response.data), p.pk)
+
+        # List all entries
+        response = self.get(url, {}, expected_code=200)
+
+        self.assertEqual(len(response.data), total)
+
+    def test_create_stocktake(self):
+        """Test that stocktake entries can be created via the API"""
+
+        url = reverse('api-part-stocktake-list')
+
+        self.assignRole('part.add')
+        self.assignRole('part.view')
+
+        for p in Part.objects.all():
+
+            # Initially no stocktake information available
+            self.assertIsNone(p.latest_stocktake)
+
+            note = f"Note {p.pk}"
+            quantity = p.pk + 5
+
+            self.post(
+                url,
+                {
+                    'part': p.pk,
+                    'quantity': quantity,
+                    'note': note,
+                },
+                expected_code=201,
+            )
+
+            p.refresh_from_db()
+            stocktake = p.latest_stocktake
+
+            self.assertIsNotNone(stocktake)
+            self.assertEqual(stocktake.quantity, quantity)
+            self.assertEqual(stocktake.part, p)
+            self.assertEqual(stocktake.note, note)
+
+    def test_edit_stocktake(self):
+        """Test that a Stoctake instance can be edited and deleted via the API.
+
+        Note that only 'staff' users can perform these actions.
+        """
+
+        p = Part.objects.all().first()
+
+        st = PartStocktake.objects.create(part=p, quantity=10)
+
+        url = reverse('api-part-stocktake-detail', kwargs={'pk': st.pk})
+        self.assignRole('part.view')
+
+        # Test we can retrieve via API
+        self.get(url, expected_code=403)
+
+        # Assign staff permission
+        self.user.is_staff = True
+        self.user.save()
+
+        self.get(url, expected_code=200)
+
+        # Try to edit data
+        self.patch(
+            url,
+            {
+                'note': 'Another edit',
+            },
+            expected_code=403
+        )
+
+        # Assign 'edit' role permission
+        self.assignRole('part.change')
+
+        # Try again
+        self.patch(
+            url,
+            {
+                'note': 'Editing note field again',
+            },
+            expected_code=200,
+        )
+
+        # Try to delete
+        self.delete(url, expected_code=403)
+
+        self.assignRole('part.delete')
+
+        self.delete(url, expected_code=204)