fix issue with awaiting cjs tests even when they return promise (that should not have been resolved)

jmuransky · jmuransky · commit b69e2de133af · 2026-04-24T15:49:54.000+02:00
diff --git a/packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapter.ts b/packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapter.ts
@@ -93,7 +93,17 @@ const jestAdapter = async (
   if (esm) {
     await runtime.unstable_importModule(testPath);
   } else {
-    await runtime.requireModuleWithEsmPreload(testPath);
+    // Await the ESM preload *before* loading the test file so that
+    // requireModule() stays synchronous.  This preserves jest-circus's
+    // async-definition detection: microtasks queued by the test file
+    // (e.g. Promise.resolve().then(() => test(...))) must not flush
+    // until after run_start has set hasStarted=true.
+    await runtime.enterCjsEsmContext(testPath);
+    try {
+      runtime.requireModule(testPath);
+    } finally {
+      runtime.leaveCjsEsmContext();
+    }
   }
 
   const setupAfterEnvPerfStats = {
diff --git a/packages/jest-jasmine2/src/index.ts b/packages/jest-jasmine2/src/index.ts
@@ -196,7 +196,14 @@ export default async function jasmine2(
   if (esm) {
     await runtime.unstable_importModule(testPath);
   } else {
-    await runtime.requireModuleWithEsmPreload(testPath);
+    // Await the ESM preload *before* loading the test file so that
+    // requireModule() stays synchronous (same timing rationale as jestAdapter).
+    await runtime.enterCjsEsmContext(testPath);
+    try {
+      runtime.requireModule(testPath);
+    } finally {
+      runtime.leaveCjsEsmContext();
+    }
   }
 
   await env.execute();
diff --git a/packages/jest-runtime/src/__tests__/runtime_esm_cjs_interop.test.ts b/packages/jest-runtime/src/__tests__/runtime_esm_cjs_interop.test.ts
@@ -114,17 +114,14 @@ describe('Runtime requireModuleWithEsmPreload', () => {
     createRuntime = require('createRuntime');
   });
 
-  itVm(
-    'allows a CJS entry file to require() an .mjs dependency',
-    async () => {
-      const runtime = await createRuntime(__filename, {rootDir: ROOT_DIR});
-      const exports = (await runtime.requireModuleWithEsmPreload(
-        FROM,
-        './cjs-requires-esm-dep.cjs',
-      )) as any;
-      expect(exports.esmValue).toBe(99);
-    },
-  );
+  itVm('allows a CJS entry file to require() an .mjs dependency', async () => {
+    const runtime = await createRuntime(__filename, {rootDir: ROOT_DIR});
+    const exports = (await runtime.requireModuleWithEsmPreload(
+      FROM,
+      './cjs-requires-esm-dep.cjs',
+    )) as any;
+    expect(exports.esmValue).toBe(99);
+  });
 });
 
 describe('Runtime loadCjsAsEsm SyntaxError fallback', () => {
diff --git a/packages/jest-runtime/src/index.ts b/packages/jest-runtime/src/index.ts
@@ -1130,21 +1130,35 @@ export default class Runtime {
   // Like requireModule but async-safe: pre-loads ESM transitive dependencies
   // before executing the CJS module so that require() calls inside it that
   // resolve to ESM files succeed (they are served from the ESM cache).
-  async requireModuleWithEsmPreload<T = unknown>(
-    from: string,
-    moduleName?: string,
-  ): Promise<T> {
+  // Preload all ESM deps reachable from the given CJS entry and arm the
+  // CJS-as-ESM flag so a subsequent synchronous requireModule() can serve
+  // those deps from the ESM registry.  Must be paired with leaveCjsEsmContext()
+  // once requireModule returns.  This two-step API lets callers (e.g.
+  // jestAdapter) put the await *before* the test file is loaded, preserving
+  // jest-circus's async-definition detection (which relies on no microtask
+  // flush happening between requireModule() and run_start being dispatched).
+  async enterCjsEsmContext(from: string, moduleName?: string): Promise<void> {
     if (runtimeSupportsVmModules) {
       const modulePath = this._resolveCjsModule(from, moduleName);
       await this._preloadEsmDependencies(modulePath);
       this._resolvingCjsAsEsm = true;
-      try {
-        return this.requireModule<T>(from, moduleName);
-      } finally {
-        this._resolvingCjsAsEsm = false;
-      }
     }
-    return this.requireModule<T>(from, moduleName);
+  }
+
+  leaveCjsEsmContext(): void {
+    this._resolvingCjsAsEsm = false;
+  }
+
+  async requireModuleWithEsmPreload<T = unknown>(
+    from: string,
+    moduleName?: string,
+  ): Promise<T> {
+    await this.enterCjsEsmContext(from, moduleName);
+    try {
+      return this.requireModule<T>(from, moduleName);
+    } finally {
+      this.leaveCjsEsmContext();
+    }
   }
 
   requireInternalModule<T = unknown>(from: string, to?: string): T {
