I just double-checked my memory. When you perform online edits of a rung, with the PLC in RUN mode, it creates a copy of that rung that isn't being scanned. Once accepted, you can test it. When you do that, the original rung is removed and the edited rung is inserted and scanned as if it were complete. If you un-test edits, it swaps the original rung back in. So, when you test edits, it will change outputs.
If you switch the PLC itself to TEST mode, then the physical outputs are not activated. I'm not sure about the inputs, since I don't have an input module wired up at the moment.