fix: call listener when setAtom changes value of atom on mount and un…

…mount

src/vanilla/store.ts

@@ -164,7 +164,7 @@ const addDependency = <Value>(
 type Pending = readonly [
   dependents: Map<AnyAtom, Set<AnyAtom>>,
   atomStates: Map<AnyAtom, AtomState>,
-  functions: Set<() => void>,
+  functions: Set<(pending: Pending) => void>,
 ]
 
 const createPending = (): Pending => [new Map(), new Map(), new Set()]
@@ -194,7 +194,10 @@ const addPendingDependent = (
 const getPendingDependents = (pending: Pending, atom: AnyAtom) =>
   pending[0].get(atom)
 
-const addPendingFunction = (pending: Pending, fn: () => void) => {
+const addPendingFunction = (
+  pending: Pending,
+  fn: (pending: Pending) => void,
+) => {
   pending[2].add(fn)
 }
 
@@ -206,7 +209,7 @@ const flushPending = (pending: Pending) => {
     const functions = new Set(pending[2])
     pending[2].clear()
     atomStates.forEach((atomState) => atomState.m?.l.forEach((l) => l()))
-    functions.forEach((fn) => fn())
+    functions.forEach((fn) => fn(pending))
   }
 }
 
@@ -574,7 +577,7 @@ const buildStore = (
       }
       if (isActuallyWritableAtom(atom)) {
         const mounted = atomState.m
-        addPendingFunction(pending, () => {
+        addPendingFunction(pending, (pending) => {
           const onUnmount = atomOnMount(atom, (...args) =>
             writeAtomState(pending, atom, ...args),
           )
@@ -620,13 +623,27 @@ const buildStore = (
     const pending = createPending()
     const atomState = getAtomState(atom)
     const mounted = mountAtom(pending, atom, atomState)
-    flushPending(pending)
     const listeners = mounted.l
     listeners.add(listener)
+    flushPending(pending)
     return () => {
       listeners.delete(listener)
       const pending = createPending()
-      unmountAtom(pending, atom, atomState)
+      const isMounted = !!unmountAtom(pending, atom, atomState)
+      const hasPrevValue = 'v' in atomState
+      const prevValue = atomState.v
+      if (!isMounted) {
+        addPendingFunction(pending, () => {
+          if (
+            !atomState.m &&
+            !isPendingPromise(atomState.v) &&
+            (!hasPrevValue || !Object.is(prevValue, atomState.v))
+          ) {
+            // call listener when setAtom changes value of atom on unmount
+            listener()
+          }
+        })
+      }
       flushPending(pending)
     }
   }