Adds test for setting model image field

bookwyrm/tests/models/test_fields.py

@@ -19,7 +19,7 @@ from django.utils import timezone
 
 from bookwyrm import activitypub
 from bookwyrm.activitypub.base_activity import ActivityObject
-from bookwyrm.models import fields, User, Status
+from bookwyrm.models import fields, User, Status, Edition
 from bookwyrm.models.base_model import BookWyrmModel
 from bookwyrm.models.activitypub_mixin import ActivitypubMixin
 from bookwyrm.settings import DOMAIN
@@ -458,6 +458,33 @@ class ModelFields(TestCase):
         self.assertIsInstance(loaded_image, list)
         self.assertIsInstance(loaded_image[1], ContentFile)
 
+    @responses.activate
+    def test_image_field_set_field_from_activity(self, *_):
+        """update a model instance from an activitypub object"""
+        image_file = pathlib.Path(__file__).parent.joinpath(
+            "../../static/images/default_avi.jpg"
+        )
+        image = Image.open(image_file)
+        output = BytesIO()
+        image.save(output, format=image.format)
+
+        instance = fields.ImageField(activitypub_field="cover", name="cover")
+
+        responses.add(
+            responses.GET,
+            "http://www.example.com/image.jpg",
+            body=image.tobytes(),
+            status=200,
+        )
+        book = Edition.objects.create(title="hello")
+
+        MockActivity = namedtuple("MockActivity", ("cover"))
+        mock_activity = MockActivity("http://www.example.com/image.jpg")
+
+        instance.set_field_from_activity(book, mock_activity)
+        self.assertIsNotNone(book.cover.name)
+        self.assertEqual(book.cover.size, 43200)
+
     def test_datetime_field(self, *_):
         """this one is pretty simple, it just has to use isoformat"""
         instance = fields.DateTimeField()