Implement ``get_image_model`` for image signals

wagtail/wagtailimages/signal_handlers.py

@@ -3,7 +3,7 @@ from __future__ import absolute_import, unicode_literals
 from django.conf import settings
 from django.db.models.signals import post_delete, pre_save
 
-from wagtail.wagtailimages.models import Image, Rendition
+from wagtail.wagtailimages import get_image_model
 
 
 def post_delete_file_cleanup(instance, **kwargs):
@@ -20,6 +20,9 @@ def pre_save_image_feature_detection(instance, **kwargs):
 
 
 def register_signal_handlers():
+    Image = get_image_model()
+    Rendition = Image.get_rendition_model()
+
     pre_save.connect(pre_save_image_feature_detection, sender=Image)
     post_delete.connect(post_delete_file_cleanup, sender=Image)
     post_delete.connect(post_delete_file_cleanup, sender=Rendition)

wagtail/wagtailimages/tests/test_signal_handlers.py

@@ -0,0 +1,31 @@
+from __future__ import absolute_import, unicode_literals
+
+import os
+
+from django.test import TestCase, override_settings
+
+from wagtail.wagtailimages import get_image_model, signal_handlers
+from wagtail.wagtailimages.tests.utils import get_test_image_file
+
+
+class TestSignalHandlers(TestCase):
+
+    def test_image_signal_handlers(self):
+        image = get_image_model().objects.create(title="Test Image", file=get_test_image_file())
+        image_path = image.file.path
+        image.delete()
+
+        self.assertFalse(os.path.exists(image_path))
+
+    @override_settings(WAGTAILIMAGES_IMAGE_MODEL='tests.CustomImage')
+    def test_custom_image_signal_handlers(self):
+        #: Sadly signal receivers only get connected when starting django.
+        #: We will re-attach them here to mimic the django startup behavior
+        #: and get the signals connected to our custom model..
+        signal_handlers.register_signal_handlers()
+
+        image = get_image_model().objects.create(title="Test CustomImage", file=get_test_image_file())
+        image_path = image.file.path
+        image.delete()
+
+        self.assertFalse(os.path.exists(image_path))