chore: add test verifying top-level await works (#10721)

Author: SimenB

e2e/__tests__/__snapshots__/nativeEsm.test.ts.snap

@@ -1,9 +1,17 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`on node >=14.3.0 supports top-level await 1`] = `
+Test Suites: 1 passed, 1 total
+Tests:       1 passed, 1 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites matching /native-esm.tla.test.js/i.
+`;
+
 exports[`on node ^12.16.0 || >=13.7.0 runs test with native ESM 1`] = `
 Test Suites: 1 passed, 1 total
 Tests:       15 passed, 15 total
 Snapshots:   0 total
 Time:        <<REPLACED>>
-Ran all test suites.
+Ran all test suites matching /native-esm.test.js/i.
 `;

e2e/__tests__/nativeEsm.test.ts

@@ -23,7 +23,7 @@ test('test config is without transform', () => {
 // The versions where vm.Module exists and commonjs with "exports" is not broken
 onNodeVersions('^12.16.0 || >=13.7.0', () => {
   test('runs test with native ESM', () => {
-    const {exitCode, stderr, stdout} = runJest(DIR, [], {
+    const {exitCode, stderr, stdout} = runJest(DIR, ['native-esm.test.js'], {
       nodeOptions: '--experimental-vm-modules',
     });
 
@@ -34,3 +34,20 @@ onNodeVersions('^12.16.0 || >=13.7.0', () => {
     expect(exitCode).toBe(0);
   });
 });
+
+// The versions where TLA is supported
+onNodeVersions('>=14.3.0', () => {
+  test('supports top-level await', () => {
+    const {exitCode, stderr, stdout} = runJest(
+      DIR,
+      ['native-esm.tla.test.js'],
+      {nodeOptions: '--experimental-vm-modules'},
+    );
+
+    const {summary} = extractSummary(stderr);
+
+    expect(wrap(summary)).toMatchSnapshot();
+    expect(stdout).toBe('');
+    expect(exitCode).toBe(0);
+  });
+});

e2e/native-esm/__tests__/native-esm-tla.test.js

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const value = await Promise.resolve('hello!');
+
+test('supports top level await', () => {
+  expect(value).toBe('hello!');
+});