Now I member

Author: eps1lon

src/__tests__/end-to-end.js

@@ -102,9 +102,27 @@ describe.each([
       React.useEffect(() => {
         if (fetchState.fetching) {
           fetchAMessageInAMicrotask().then(res => {
-            return res.json().then(data => {
-              setFetchState({todo: data.title, fetching: false})
-            })
+            return (
+              res
+                .json()
+                // By spec, the runtime can only yield back to the event loop once
+                // the microtask queue is empty.
+                // So we ensure that we actually wait for that as well before yielding back from `waitFor`.
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => data)
+                .then(data => {
+                  setFetchState({todo: data.title, fetching: false})
+                })
+            )
           })
         }
       }, [fetchState])

src/pure.js

@@ -12,6 +12,20 @@ import act, {
 } from './act-compat'
 import {fireEvent} from './fire-event'
 
+function jestFakeTimersAreEnabled() {
+  /* istanbul ignore else */
+  if (typeof jest !== 'undefined' && jest !== null) {
+    return (
+      // legacy timers
+      setTimeout._isMockFunction === true || // modern timers
+      // eslint-disable-next-line prefer-object-has-own -- No Object.hasOwn in all target environments we support.
+      Object.prototype.hasOwnProperty.call(setTimeout, 'clock')
+    )
+  } // istanbul ignore next
+
+  return false
+}
+
 configureDTL({
   unstable_advanceTimersWrapper: cb => {
     return act(cb)
@@ -27,7 +41,15 @@ configureDTL({
       // Drain microtask queue.
       // Otherwise we'll restore the previous act() environment, before we resolve the `waitFor` call.
       // The caller would have no chance to wrap the in-flight Promises in `act()`
-      await Promise.resolve().then(() => {})
+      await new Promise(resolve => {
+        setTimeout(() => {
+          resolve()
+        }, 0)
+
+        if (jestFakeTimersAreEnabled()) {
+          jest.advanceTimersByTime(0)
+        }
+      })
 
       return result
     } finally {