Test MediaViewModel

[robintown]

This was the result of me playing around with RxJS marble testing to understand how to get things done with its TestScheduler. I discovered that it lacks a clear way to fire arbitrary actions during the test, so I built a small helper function called schedule which does this for us.

[toger5]

Cool this looks nice.
I am not sure where exactly it makes the most sense to do the abstraction cut.
creating the new testScheduler and using the deep.equals from vitest definitely should be abstracted.
I think we might also want a withTestScheduler that does not enforce the marbles -> action pattern. So I am wondering if we should already call it withActionTestScheduler? (easy to refactor afterwards however so I will approve for now.

[robintown]

I think we might also want a withTestScheduler that does not enforce the marbles -> action pattern.

What do you mean by this? Are you saying it would be nice to have a variant that lets you run observables and actions in real time? That's what you already get when writing a test without TestScheduler.

[toger5]

I am wondering if this:

export function withTestScheduler(
  continuation: (helpers: OurRunHelpers) => void,
): void {
  new TestScheduler((actual, expected) => {
    expect(actual).deep.equals(expected);
  }).run((helpers) =>
    continuation(helpers),
  );
}

On its own is already helpful?
But thinking it through:

withTestScheduler((helpers)=>{
  // some custom rxjs testing
  helpers.cold("some_marbels").pipe(...);
  // some custom checks
  helpers.expectObservable()...;
})

VS

new TestScheduler((actual, expected) => {
  expect(actual).deep.equals(expected);
}).run((helpers) =>
  // some custom rxjs testing
  helpers.cold("some_marbels").pipe(...);
  // some custom checks
  helpers.expectObservable()...;
);

might not be enough of a simplification to justify the reduced explicity.