Check that destroyed state creates no new object (test_request_destroyed_state).
Check that simple case of requesting two different instances works correctly
(test_request_two_different).
Check that changes to tree structure are applied correctly for indexed tree
(test_request_tree_change_indexed) and that they are forbidden in other cases
(test_request_tree_change_not_indexed and test_request_tree_change_same_transaction,
where the former is a low severity bug, so expectedFailure).
Check that state is correctly propagated (test_request_started_stopped_destroyed).