Cypress test should send unsubscribe_rooms for every room switch seems flakey

[DMRobertson]

e.g. https://github.com/matrix-org/sliding-sync/actions/runs/4482864263/jobs/7881442972

      AssertionError: room_subscriptions is object: expected undefined to be an object

[kegsay]

Related: #42 ? Need to check video.

[DMRobertson]

And https://github.com/matrix-org/sliding-sync/actions/runs/4553358923/jobs/8029820210 , which should now have a video at https://github.com/matrix-org/sliding-sync/actions/runs/4553358923

[DMRobertson]

And https://github.com/matrix-org/sliding-sync/actions/runs/4613554076/jobs/8155657605#step:9:2435

[DMRobertson]

I spent an hour or so looking into this. From what I can see, the react/js sdk maintains an explicit subscription to whichever room is open in the client. (You still want to see updates that room, even if it's outside of your sliding window(s).)

AFAICS The room_subscriptions field is populated here, whenever newSubscriptions is nonempty.

https://github.com/matrix-org/matrix-js-sdk/blob/c805b7e29d6c8fd592112df8acc7ea78c532db5e/src/sliding-sync.ts#L850-L866

newSubscriptions is the set difference this.desiredRoomSubscriptions - this.confirmedRoomSubscriptions. So the room we're looking for is either not desired, already confirmed, or both when we see this failure mode.

I guess the next step would be to get the SDK to log those sets and somehow get CI to expose those logs to us.

[DMRobertson]

I haven't seen this fail in a while. Maybe something got fixed in the react/js sdk?

[DMRobertson]

Let's assume this magically unflaked itself, and reopen if not.

[DMRobertson]

Let's assume this magically unflaked itself, and reopen if not.

Spoke too soon. https://github.com/matrix-org/sliding-sync/actions/runs/5598990176/jobs/10239377271