From 7a6b5e40d96bef59659c40d6a187717f8b70adc1 Mon Sep 17 00:00:00 2001
From: Marc Rousavy <me@mrousavy.com>
Date: Sat, 5 Sep 2026 16:02:19 +0300
Subject: [PATCH] test: Check promise concurrency without wall-clock timing

---
 apps/example/src/getTests.ts | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/apps/example/src/getTests.ts b/apps/example/src/getTests.ts
index 0c698e436..d5a1c47e9 100644
--- a/apps/example/src/getTests.ts
+++ b/apps/example/src/getTests.ts
@@ -1572,12 +1572,22 @@ export function getTests(
     createTest('twoPromises can run in parallel', async () =>
       (
         await it(async () => {
-          const start = performance.now()
-          // 0.5s + 0.5s = ~1s in serial, ~0.5s in parallel
-          await Promise.all([testObject.wait(0.5), testObject.wait(0.5)])
-          const end = performance.now()
-          const didRunInParallel = end - start < 1000
-          return didRunInParallel
+          let started = 0
+          let release = () => {}
+          const bothStarted = new Promise<void>((resolve) => {
+            release = resolve
+          })
+          const onStarted = () => {
+            started++
+            if (started === 2) release()
+            return bothStarted
+          }
+          // Each native operation waits until both have invoked their callback.
+          await Promise.all([
+            testObject.callCallbackThatReturnsPromiseVoid(onStarted),
+            testObject.callCallbackThatReturnsPromiseVoid(onStarted),
+          ])
+          return started === 2
         })
       )
         .didNotThrow()