Add unit tests for the 'locate' plugin

- Test various failure modes
- Some of the failure modes didn't fail - this is also a failure
- Fixing API code accordingly

InvenTree/plugin/base/locate/api.py

@@ -40,9 +40,6 @@ class LocatePluginView(APIView):
         # StockLocation to identify
         location_pk = request.data.get('location', None)
 
-        if not item_pk and not location_pk:
-            raise ParseError("Must supply either 'item' or 'location' parameter")
-
         data = {
             "success": "Identification plugin activated",
             "plugin": plugin,
@@ -59,8 +56,8 @@ class LocatePluginView(APIView):
 
                 return Response(data)
 
-            except StockItem.DoesNotExist:
-                raise NotFound("StockItem matching PK '{item}' not found")
+            except (ValueError, StockItem.DoesNotExist):
+                raise NotFound(f"StockItem matching PK '{item_pk}' not found")
 
         elif location_pk:
             try:
@@ -72,8 +69,9 @@ class LocatePluginView(APIView):
 
                 return Response(data)
 
-            except StockLocation.DoesNotExist:
-                raise NotFound("StockLocation matching PK {'location'} not found")
+            except (ValueError, StockLocation.DoesNotExist):
+                raise NotFound(f"StockLocation matching PK '{location_pk}' not found")
 
         else:
-            raise NotFound()
+            raise ParseError("Must supply either 'item' or 'location' parameter")
+

InvenTree/plugin/base/locate/test_locate.py

@@ -0,0 +1,89 @@
+"""
+Unit tests for the 'locate' plugin mixin class
+"""
+
+from django.urls import reverse
+
+from InvenTree.api_tester import InvenTreeAPITestCase
+
+from plugin.registry import registry
+
+
+class LocatePluginTests(InvenTreeAPITestCase):
+
+    fixtures = [
+        'category',
+        'part',
+        'location',
+        'stock',
+    ]
+
+    def test_installed(self):
+        """Test that a locate plugin is actually installed"""
+
+        plugins = registry.with_mixin('locate')
+
+        self.assertTrue(len(plugins) > 0)
+
+        self.assertTrue('samplelocate' in [p.slug for p in plugins])
+
+    def test_locate_fail(self):
+        """Test various API failure modes"""
+        
+        url = reverse('api-locate-plugin')
+
+        # Post without a plugin
+        response = self.post(
+            url,
+            {},
+            expected_code=400
+        )
+
+        self.assertIn("'plugin' field must be supplied", str(response.data))
+
+        # Post with a plugin that does not exist, or is invalid
+        for slug in ['xyz', 'event', 'plugin']:
+            response = self.post(
+                url,
+                {
+                    'plugin': slug,
+                },
+                expected_code=400,
+            )
+
+            self.assertIn(f"Plugin '{slug}' is not installed, or does not support the location mixin", str(response.data))
+
+        # Post with a valid plugin, but no other data
+        response = self.post(
+            url,
+            {
+                'plugin': 'samplelocate',
+            },
+            expected_code=400
+        )
+
+        self.assertIn("Must supply either 'item' or 'location' parameter", str(response.data))
+
+        # Post with valid plugin, invalid item or location
+        for pk in ['qq', 99999, -42]:
+            response = self.post(
+                url,
+                {
+                    'plugin': 'samplelocate',
+                    'item': pk,
+                },
+                expected_code=404
+            )
+
+            self.assertIn(f"StockItem matching PK '{pk}' not found", str(response.data))
+
+            response = self.post(
+                url,
+                {
+                    'plugin': 'samplelocate',
+                    'location': pk,
+                },
+                expected_code=404,
+            )
+
+            self.assertIn(f"StockLocation matching PK '{pk}' not found", str(response.data))