diff --git a/bookwyrm/tests/models/test_fields.py b/bookwyrm/tests/models/test_fields.py
index e7393096..2b2d3939 100644
--- a/bookwyrm/tests/models/test_fields.py
+++ b/bookwyrm/tests/models/test_fields.py
@@ -1,11 +1,20 @@
 ''' testing models '''
+from io import BytesIO
 from collections import namedtuple
+import pathlib
+import re
+
+from PIL import Image
+import responses
 
 from django.core.exceptions import ValidationError
+from django.core.files.base import ContentFile
 from django.db import models
 from django.test import TestCase
+from django.utils import timezone
 
-from bookwyrm.models import fields
+from bookwyrm.models import fields, User
+from bookwyrm.settings import DOMAIN
 
 class ActivitypubFields(TestCase):
     def test_validate_remote_id(self):
@@ -103,3 +112,78 @@ class ActivitypubFields(TestCase):
             instance.field_to_activity(items),
             'example.com/snake_case'
         )
+
+    def test_tag_field(self):
+        instance = fields.TagField('User')
+
+        Serializable = namedtuple(
+            'Serializable',
+            ('to_activity', 'remote_id', 'name_field', 'name')
+        )
+        Queryset = namedtuple('Queryset', ('all', 'instance'))
+        item = Serializable(
+            lambda: {'a': 'b'}, 'https://e.b/c', 'name', 'Name')
+        another_item = Serializable(
+            lambda: {}, 'example.com', '', '')
+        items = Queryset(lambda: [item], another_item)
+
+        result = instance.field_to_activity(items)
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 1)
+        self.assertEqual(result[0].href, 'https://e.b/c')
+        self.assertEqual(result[0].name, 'Name')
+        self.assertEqual(result[0].type, 'Serializable')
+
+
+    @responses.activate
+    def test_image_field(self):
+        user = User.objects.create_user(
+            'mouse', 'mouse@mouse.mouse', 'mouseword', local=True)
+        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)
+        user.avatar.save(
+            'test.jpg',
+            ContentFile(output.getvalue())
+        )
+
+        output = fields.image_serializer(user.avatar)
+        self.assertIsNotNone(
+            re.match(
+                r'https://%s/images/avatars/test_[A-z0-9]+\.jpg' % DOMAIN,
+                output.url,
+            )
+        )
+        self.assertEqual(output.type, 'Image')
+
+        instance = fields.ImageField()
+
+        self.assertEqual(instance.field_to_activity(user.avatar), output)
+
+        responses.add(
+            responses.GET,
+            'http://www.example.com/image.jpg',
+            body=user.avatar.file.read(),
+            status=200)
+        loaded_image = instance.field_from_activity(
+            'http://www.example.com/image.jpg')
+        self.assertIsInstance(loaded_image, list)
+        self.assertIsNotNone(re.match(r'.*\.jpg', loaded_image[0]))
+        self.assertIsInstance(loaded_image[1], ContentFile)
+
+
+    def test_datetime_field(self):
+        instance = fields.DateTimeField()
+        now = timezone.now()
+        self.assertEqual(instance.field_to_activity(now), now.isoformat())
+        self.assertEqual(
+            instance.field_from_activity(now.isoformat()), now
+        )
+        self.assertEqual(instance.field_from_activity('bip'), None)
+
+
+    def test_array_field(self):
+        instance = fields.ArrayField(fields.IntegerField)
+        self.assertEqual(instance.field_to_activity([0, 1]), ['0', '1'])