fix(ci): yield the event loop between script tests to avoid vitest RPC timeouts (#10037)

scripts/tests/event-loop-yield.test.js

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright 2026 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { expect, it } from 'vitest';
+
+// Pins the invariant established by test-setup.ts's beforeEach yield:
+// between two tests the worker's event loop must turn far enough to drain
+// pending macrotasks. Without that yield a fully synchronous file never
+// reaches the timer phase between tests, the flag armed below never flips,
+// and the same unbroken stall is what lets vitest's fixed 60s worker->main
+// `onTaskUpdate` RPC timeout fire (see test-setup.ts).
+let macrotaskRan = false;
+
+it('arms a flag from a real macrotask callback', () => {
+  setTimeout(() => {
+    macrotaskRan = true;
+  }, 0);
+});
+
+it('observes the event loop turned between tests', () => {
+  expect(macrotaskRan).toBe(true);
+});

scripts/tests/test-setup.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { vi } from 'vitest';
+import { beforeEach, vi } from 'vitest';
 
 vi.mock('fs', async () => {
   const actual = await vi.importActual<typeof import('fs')>('fs');
@@ -18,3 +18,15 @@ vi.mock('fs', async () => {
     },
   };
 });
+
+// Captured before any test can install fake timers, so this yield always
+// uses the real timer. Suites made of synchronous spawnSync tests can keep
+// a worker's event loop blocked for the whole file (>60s), which makes
+// vitest's fixed 60s worker->main `onTaskUpdate` RPC timeout fire and the
+// run exit 1 with every test green. Yielding between tests bounds any
+// continuous stall to a single test, so the RPC response drains well before
+// the deadline. (A single test, beforeAll, or module-level block stalling
+// for 60s would still trip it: testTimeout cannot interrupt synchronous
+// bodies.)
+const realSetTimeout = setTimeout;
+beforeEach(() => new Promise((resolve) => realSetTimeout(resolve, 0)));