Use the Object Spy tool on the control that has the scroll bar to see if there's anything relating to the property scroll bar visibility. In most cases, I don't think there will be a property for standard control.
You can use the error message "unable to find error" as scroll bar not visible.
For example, Notepad has the following
VScrollBar, no HScrollBar
VScrollBar, disabled HScrollBar
VScrollBar and HScrollBar
HScrollBar will return Pos: 0, Min:0 Max: 0 for either disabled or no scroll bar. So this can be treated as disabled or no scroll bar for your test. There's no other property value for this scroll bar.
