fix: avoid multiple subscriptions with empty promises

Fix #1129

Author: posva

packages/pinia/__tests__/subscriptions.spec.ts

@@ -202,7 +202,7 @@ describe('Subscriptions', () => {
       expect(spy2).toHaveBeenCalledTimes(1)
     })
 
-    it.skip('triggers pre subscriptions only once on $patch', async () => {
+    it('triggers pre subscriptions only once on $patch', async () => {
       const s1 = useStore()
       const spy1 = jest.fn()
 
@@ -216,7 +216,7 @@ describe('Subscriptions', () => {
       // adding an extra await works
       // await false
       // adding any other delay also works
-      await delay(20)
+      // await delay(20)
       // await nextTick()
       expect(spy1).toHaveBeenCalledTimes(1)
       expect(spy1).not.toHaveBeenCalledWith(

packages/pinia/src/store.ts

@@ -252,6 +252,9 @@ function createSetupStore<
 
   const hotState = ref({} as S)
 
+  // avoid triggering too many listeners
+  // https://github.com/vuejs/pinia/issues/1129
+  let activeListener: Symbol | undefined
   function $patch(stateMutation: (state: UnwrapRef<S>) => void): void
   function $patch(partialState: _DeepPartial<UnwrapRef<S>>): void
   function $patch(
@@ -282,8 +285,11 @@ function createSetupStore<
         events: debuggerEvents as DebuggerEvent[],
       }
     }
+    const myListenerId = (activeListener = Symbol())
     nextTick().then(() => {
-      isListening = true
+      if (activeListener === myListenerId) {
+        isListening = true
+      }
     })
     isSyncListening = true
     // because we paused the watcher, we need to manually call the subscriptions