Custom 500 error message should only be seen for Preview

common/djangoapps/util/views.py

@@ -56,13 +56,18 @@ def jsonable_server_error(request, template_name='500.html'):
         return server_error(request, template_name=template_name)
 
 
-def handle_500(template_path, context=None):
+def handle_500(template_path, context=None, test_func=None):
     """
     Decorator for view specific 500 error handling.
+    Custom handling will be skipped only if test_func is passed and it returns False
 
-    Usage::
+    Usage:
 
-        @handle_500(template_path='certificates/server-error.html', context={'error-info': 'Internal Server Error'})
+        @handle_500(
+            template_path='certificates/server-error.html',
+            context={'error-info': 'Internal Server Error'},
+            test_func=lambda request: request.GET.get('preview', None)
+        )
         def my_view(request):
             # Any unhandled exception in this view would be handled by the handle_500 decorator
             # ...
@@ -83,9 +88,15 @@ def handle_500(template_path, context=None):
                 if settings.DEBUG:
                     # In debug mode let django process the 500 errors and display debug info for the developer
                     raise
-                else:
+                elif test_func is None or test_func(request):
+                    # Display custom 500 page if either
+                    #   1. test_func is None (meaning nothing to test)
+                    #   2. or test_func(request) returns True
                     log.exception("Error in django view.")
                     return render_to_response(template_path, context)
+                else:
+                    # Do not show custom 500 error when test fails
+                    raise
         return inner
     return decorator