#10886 follow-up

Right now, we only generate tests for Move(). That's great! But we could/should easily adapt it to test some other APIs like:

• ExpandToEnclosingUnit()
• MoveEndpointByUnit()

We may also be able to add tests that make sure we work with clones properly. Like...

• create a clone --> "move" the clone --> clone should not be the same as original
• create a clone --> "move" the clone --> "move" the original the same way --> both should be the same