alternate fix

src/vanilla/store.ts

@@ -566,11 +566,17 @@ const buildStore = (...storeArgs: StoreArgs): Store => {
 
   const mountDependencies = (atom: AnyAtom, atomState: AtomState) => {
     if (atomState.m && !isPendingPromise(atomState.v)) {
-      for (const a of atomState.d.keys()) {
+      for (const [a, n] of atomState.d) {
         if (!atomState.m.d.has(a)) {
-          const aMounted = mountAtom(a, ensureAtomState(a))
+          const aState = ensureAtomState(a)
+          const aMounted = mountAtom(a, aState)
           aMounted.t.add(atom)
           atomState.m.d.add(a)
+          if (n !== aState.n) {
+            changedAtoms.set(a, aState)
+            aState.u?.()
+            invalidateDependents(aState)
+          }
         }
       }
       for (const a of atomState.m.d || []) {

tests/vanilla/dependency.test.tsx

@@ -1,6 +1,5 @@
 import { expect, it, vi } from 'vitest'
 import { atom, createStore } from 'jotai/vanilla'
-import { createDebugStore } from '../../tests/testUtils'
 
 it('can propagate updates with async atom chains', async () => {
   const store = createStore()
@@ -426,95 +425,3 @@ it('batches sync writes', () => {
   expect(fetch).toBeCalledWith(1)
   expect(store.get(a)).toBe(1)
 })
-
-it('mounts and unmounts sync and async dependencies correctly', async () => {
-  const mounted = [0, 0, 0, 0, 0] as [number, number, number, number, number]
-  const a = atom(0)
-  a.debugLabel = 'a'
-  a.onMount = () => {
-    ++mounted[0]
-    return () => {
-      --mounted[0]
-    }
-  }
-
-  const b = atom(0)
-  b.debugLabel = 'b'
-  b.onMount = () => {
-    ++mounted[1]
-    return () => {
-      --mounted[1]
-    }
-  }
-
-  const c = atom(0)
-  c.debugLabel = 'c'
-  c.onMount = () => {
-    ++mounted[2]
-    return () => {
-      --mounted[2]
-    }
-  }
-
-  const d = atom(0)
-  d.debugLabel = 'd'
-  d.onMount = () => {
-    ++mounted[3]
-    return () => {
-      --mounted[3]
-    }
-  }
-
-  const e = atom(0)
-  e.debugLabel = 'e'
-  e.onMount = () => {
-    ++mounted[4]
-    return () => {
-      --mounted[4]
-    }
-  }
-
-  let resolve: (() => Promise<void>) | undefined
-  const f = atom((get) => {
-    if (!get(a)) {
-      get(b)
-    } else {
-      get(c)
-    }
-    const promise = new Promise<void>((r) => {
-      resolve = () => {
-        r()
-        return promise
-      }
-    }).then(() => {
-      if (!get(a)) {
-        get(d)
-      } else {
-        get(e)
-      }
-    })
-    return promise
-  })
-  f.debugLabel = 'f'
-
-  const store = createDebugStore()
-  // mount a, b synchronously
-  const unsub = store.sub(f, () => {})
-  expect(mounted).toEqual([1, 1, 0, 0, 0])
-
-  // mount d asynchronously
-  await resolve!()
-  expect(mounted).toEqual([1, 1, 0, 1, 0])
-
-  // unmount b, mount c synchronously
-  store.set(a, 1)
-  expect(mounted).toEqual([1, 0, 1, 1, 0])
-
-  // unmount d, mount e asynchronously
-  await resolve!()
-  expect(mounted).toEqual([1, 0, 1, 0, 1])
-
-  // unmount a, b, d, e synchronously
-  unsub()
-  expect(mounted).toEqual([0, 0, 0, 0, 0])
-})