test: should update dependents with the value of the unwrapped atom when the promise resolves

Author: dmaskasky

src/vanilla/utils/unwrap.ts

@@ -44,6 +44,7 @@ export function unwrap<Value, Args extends unknown[], Result, PendingValue>(
       const promiseErrorCache = new WeakMap<Promise<unknown>, unknown>()
       const promiseResultCache = new WeakMap<Promise<unknown>, Awaited<Value>>()
       const refreshAtom = atom(0)
+      refreshAtom.debugLabel = 'refresh'
 
       if (import.meta.env?.MODE !== 'production') {
         refreshAtom.debugPrivate = true
@@ -89,14 +90,15 @@ export function unwrap<Value, Args extends unknown[], Result, PendingValue>(
           set(refreshAtom, (c) => c + 1)
         },
       )
+      promiseAndValueAtom.debugLabel = 'promiseAndValue'
       // HACK to read PromiseAndValue atom before initialization
       promiseAndValueAtom.init = undefined
 
       if (import.meta.env?.MODE !== 'production') {
         promiseAndValueAtom.debugPrivate = true
       }
 
-      return atom(
+      const unwrappedAtom = atom(
         (get) => {
           const state = get(promiseAndValueAtom)
           if ('f' in state) {
@@ -108,6 +110,8 @@ export function unwrap<Value, Args extends unknown[], Result, PendingValue>(
         (_get, set, ...args) =>
           set(anAtom as WritableAtom<Value, unknown[], unknown>, ...args),
       )
+      unwrappedAtom.debugLabel = 'unwrapped'
+      return unwrappedAtom
     },
     anAtom,
     fallback,

tests/vanilla/utils/unwrap.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import { atom, createStore } from 'jotai/vanilla'
+import type { Atom, Getter, Setter } from 'jotai/vanilla'
 import { unwrap } from 'jotai/vanilla/utils'
 
 describe('unwrap', () => {
@@ -150,3 +151,17 @@ describe('unwrap', () => {
     expect(store.get(syncAtom)).toEqual('concrete')
   })
 })
+
+it('should update dependents with the value of the unwrapped atom when the promise resolves', async () => {
+  const store = createStore()
+  const asyncTarget = atom(() => Promise.resolve('value'))
+  const target = unwrap(asyncTarget)
+  const results: string[] = []
+  const derived = atom(async (get) => {
+    await Promise.resolve()
+    results.push('effect ' + get(target))
+  })
+  store.sub(derived, () => {})
+  await new Promise((r) => setTimeout(r))
+  expect(results).toEqual(['effect undefined', 'effect value'])
+})