Validate image size in pixels at upload time (#3003)

src/tests/api/test_order_change.py

@@ -31,6 +31,7 @@ from django.utils.timezone import now
 from django_countries.fields import Country
 from django_scopes import scopes_disabled
 from pytz import UTC
+from tests.const import SAMPLE_PNG
 
 from pretix.base.models import (
     InvoiceAddress, Order, OrderPosition, Question, SeatingPlan,
@@ -1018,7 +1019,7 @@ def test_position_update_question_handling(token_client, organizer, event, order
         '/api/v1/upload',
         data={
             'media_type': 'image/png',
-            'file': ContentFile('file.png', 'invalid png content')
+            'file': ContentFile(SAMPLE_PNG)
         },
         format='upload',
         HTTP_CONTENT_DISPOSITION='attachment; filename="file.png"',