Android navigation bar during testing prototype with users

please advise me…
Do you add android navigation bar to screens and do you use it during testing prototype with users? I mean this bar used for android phones without any physical buttons.

Android navigation buttons added to prototype screen

I ask for it because when you use real mobile app you use these buttons or every action. Especially navigation button for going back, to return.

There are not any other options how to get back to previous step or screen during the testing the prototype. Just to add special button for going back. See circled angle bracket “<”

How do you solve this problem please?


I have the same question D: