[@xstate/store] Fix synchronous updates through nested atom dependencies and subscriptions

[thecrypticace]

Fix synchronous subscribe callbacks still not re-running if a subscription triggers another one through multiple levels of computed atoms.

---

Turns out checking for the dirty state wasn't enough — I needed to check for the pending state as well.

Essentially the following test currently fails but now passes after this PR:

it('allows updates to a computed dependency during a subscription callback', () => {
  const atom = createAtom({ a: 0, b: 0, c: 0 });

  const a0 = createAtom(() => atom.get().a);
  const a1 = createAtom(() => a0.get());
  a1.subscribe(() => atom.set((ctx) => ({ ...ctx, b: ctx.a })));

  const b0 = createAtom(() => atom.get().b);
  const b1 = createAtom(() => b0.get());
  b1.subscribe(() => atom.set((ctx) => ({ ...ctx, c: ctx.b })));

  atom.set((ctx) => ({ ...ctx, a: ctx.a + 1 }));
  atom.set((ctx) => ({ ...ctx, a: ctx.a + 1 }));
  atom.set((ctx) => ({ ...ctx, a: ctx.a + 1 }));

  expect(a0.get()).toBe(3);
  expect(a1.get()).toBe(3);
  expect(b0.get()).toBe(3);
  expect(b1.get()).toBe(3);
  expect(atom.get().a).toBe(3);
  expect(atom.get().b).toBe(3);
  expect(atom.get().c).toBe(3);
});

This happens because b1's subscription callback runs during a1's subscription callback (which the previous PR handled) but the state of the atom is different in this particular case.

[changeset-bot]

🦋 Changeset detected

Latest commit: 10eb104

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 7 packages

Name	Type
@xstate/store	Patch
@xstate/store-angular	Patch
@xstate/store-preact	Patch
@xstate/store-react	Patch
@xstate/store-solid	Patch
@xstate/store-svelte	Patch
@xstate/store-vue	Patch

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[thecrypticace]

since atom.get() does an if check already it's probably okay to just drop this if entirely? Thoughts?

[davidkpiano]

Give it a try; if the tests pass I'd say it's safe

[thecrypticace]

They do 👍