Merge ~sylvain-pineau/plainbox:empty_resource into plainbox:master

[Sylvain Pineau]

This patch avoids job requirements to fail if one resource object has no records.

Tested with mediacard/sd-preinserted on a system with no snaps installed

[Maciej Kisielewski (kissiel)]

I like it!

review: Approve

diff --git a/plainbox/impl/ctrl.py b/plainbox/impl/ctrl.py
index 0ad1a47..ac019fa 100644
--- a/plainbox/impl/ctrl.py
+++ b/plainbox/impl/ctrl.py
@@ -295,6 +295,9 @@ class CheckBoxSessionStateController(ISessionStateController):
             logger.info(
                 _("Storing resource record %r: %s"), job.id, resource)
             new_resource_list.append(resource)
+        # Create an empty resource object to properly fail __getattr__ calls
+        if not new_resource_list:
+            new_resource_list = [Resource({})]
         # Replace any old resources with the new resource list
         session_state.set_resource_list(job.id, new_resource_list)