Why OR-AND operators do not work with ISSUE IN ..?

Question

I find it quite silly that the following does not work (or rather even worse, it returns a wrong number and thus it cannot be relied upon):

issue in testExecutionTests("X") or issue in testExecutionTests("Y")

This only returns tests from Y, the first query (for X) is ignored.

What is the problem here?

P_ · Answer

Independently they work just fine.

Nic Brough -Adaptavist- · Answer

What do the two clauses return when run on their own?