Hi @Saira ,
You can select an issue > click Test > click View result for more script validator log.
Your script currently wrong syntax, it should be issue.parent.assignee.accountId != issue.assignee.accountId
If your issue-parent is issue - sub-task.
Hope this helps!
One more question - now that you helped answer my first one :D
I have a parent issue that has two subtasks - suppose task A and task B
I want task B's assignee to not be the same as task A's. Task A has a label, let's call that X.
How do I write a scriptrunner script to restrict transition of task B if task A and B have the same assignee ?