improve tests

Author: vchrisb

tests/test_models.py

@@ -8,9 +8,12 @@
 from django.conf import settings
 from django.core.files.storage import default_storage
 from django.core.files.uploadedfile import SimpleUploadedFile
+from django.db.models.fields.files import ImageFieldFile
 from django.utils import version
 from PIL import Image
 
+from stdimage.models import StdImageFieldFile
+
 from . import models
 from .models import (
     AdminDeleteModel,
@@ -184,9 +187,14 @@ def test_variations_deepcopy(self, db):
             image=self.fixtures["600x400.jpg"]
         )
         instance = copy.deepcopy(instance_original)
+        assert isinstance(instance.image, StdImageFieldFile)
+
         assert hasattr(instance.image, "thumbnail")
         assert hasattr(instance.image, "medium")
 
+        assert isinstance(instance.image.thumbnail, ImageFieldFile)
+        assert isinstance(instance.image.medium, ImageFieldFile)
+
         source_file = self.fixtures["600x400.jpg"]
 
         assert os.path.exists(os.path.join(IMG_DIR, "600x400.jpg"))