I have recorded clicking on a button in a tab bar using Xcode 9.1's UITest record button. The recorded interaction in Test.swift appears below:
It's unclear to me what the downward caret means or does. Can someone provide a nice explanation? Apple's UITest documentation did not help me.
The caret means that Xcode knows there are other ways to access that user interface element. Click the caret for a menu of all the ways Xcode knows how to access it:
Brooke Callahan demonstrates this in WWDC 2015 Session 406 “UI Testing in Xcode” starting around 34:10. He refers to the carets as “tokens”.