Testing Pointer Lock

Pointer lock is tricky to automate tests for. Consider some examples:
- Upon lock, no pointer should be visible.
- A user gesture is required to lock when not in fullscreen.
- Transitioning to fullscreen and pointer lock then exiting fullscreen
should maintain pointer lock. (User gesture required to enter fullscreen)
- While locked, moving the mouse indefinitely in any direction must
continue to provide non zero movementX/Y values.

I'm considering starting some pointer lock tests with testharness.js. The
only solution I see is to provide instructions in many tests
for manual actions and observations.

I appreciate any best practice suggestions, or pointers to other
specifications with similar challenges. So far I see geolocation tests
provide manual instructions.