What needs testing in a shared Spectacles experience?
More than two people seeing the same object once. Test joining late, leaving, delayed updates and reconnection. The application needs a clear owner for shared state and a defined view of that state for each participant.
Decide which event wins
Suppose two participants change the same item while one connection is delayed. The app needs a rule for resolving the updates. We would decide that rule explicitly rather than allowing whichever packet arrives last to determine the experience accidentally.
Start with a shared counter or selection. Have one participant disconnect, change the value with the other, then reconnect the first. The expected result should be written down before the test. That small example makes state ownership and recovery easier to reason about than a complex collaborative scene.