TestScheduler: Allow expectObservable to schedule observable subscription at non-0 time.

[12wrigja]

Feature Request

In order to provide more control over timings in tests created using TestScheduler, allow expectObservable to start observable subscription at a non-0 time. This would allow for TestScheduler to better schedule sets of expectations which start at different times.

As expectObservable already accepts a subscription diagram, this change could simply involve using the start time in that diagram (if present) as the initial subscription time. I have a change that does this I can propose.

My primary use-case for this sort of behavior is testing that subscribing to an observable at two different times does not cause repeat work in a service that it depends on. Currently, I can't offset the second subscription to the method, and it makes the tests less effective.

[cartant]

Have a look at #3997

[12wrigja]

Thanks! Interesting how similar our proposals are. Looking forward to seeing this merged.

[cartant]

Yeah, I will remember to mention - in the team meeting - that it was feature that you've requested, too.