Add unit tests for .webp support

InvenTree/part/test_api.py

@@ -970,12 +970,16 @@ class PartDetailTests(InvenTreeAPITestCase):
             )
 
             self.assertEqual(response.status_code, 400)
+            self.assertIn('Upload a valid image', str(response.data))
+
+        # Now try to upload a valid image file, in multiple formats
+        for fmt in ['jpg', 'png', 'bmp', 'webp']:
+            fn = f'dummy_image.{fmt}'
 
-        # Now try to upload a valid image file
             img = PIL.Image.new('RGB', (128, 128), color='red')
-        img.save('dummy_image.jpg')
+            img.save(fn)
 
-        with open('dummy_image.jpg', 'rb') as dummy_image:
+            with open(fn, 'rb') as dummy_image:
                 response = upload_client.patch(
                     url,
                     {
@@ -988,6 +992,7 @@ class PartDetailTests(InvenTreeAPITestCase):
 
             # And now check that the image has been set
             p = Part.objects.get(pk=pk)
+            self.assertIsNotNone(p.image)
 
     def test_details(self):
         """