esm: increase test coverage of edge cases

PR-URL: https://github.com/nodejs/node/pull/47033
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Jacob Smith <jacob@frende.me>

test/es-module/test-esm-loader-hooks.mjs

@@ -67,6 +67,21 @@ describe('Loader hooks', { concurrency: true }, () => {
       assert.strictEqual(code, 0);
       assert.strictEqual(signal, null);
     });
+
+    it('import.meta.resolve of a never-settling resolve', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-import-meta-resolve',
+        '--experimental-loader',
+        fixtures.fileURL('es-module-loaders/never-settling-resolve-step/loader.mjs'),
+        fixtures.path('es-module-loaders/never-settling-resolve-step/import.meta.never-resolve.mjs'),
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.match(stdout, /^should be output\r?\n$/);
+      assert.strictEqual(code, 13);
+      assert.strictEqual(signal, null);
+    });
   });
 
   describe('should handle never-settling hooks in CJS files', { concurrency: true }, () => {
@@ -165,4 +180,19 @@ describe('Loader hooks', { concurrency: true }, () => {
     assert.strictEqual(code, 1);
     assert.strictEqual(signal, null);
   });
+
+  it('should not leak internals or expose import.meta.resolve', async () => {
+    const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--experimental-import-meta-resolve',
+      '--experimental-loader',
+      fixtures.fileURL('es-module-loaders/loader-edge-cases.mjs'),
+      fixtures.path('empty.js'),
+    ]);
+
+    assert.strictEqual(stderr, '');
+    assert.strictEqual(stdout, '');
+    assert.strictEqual(code, 0);
+    assert.strictEqual(signal, null);
+  });
 });

test/fixtures/es-module-loaders/loader-edge-cases.mjs

@@ -0,0 +1,15 @@
+import { strictEqual } from "node:assert";
+import { isMainThread, workerData, parentPort } from "node:worker_threads";
+
+// TODO(aduh95): switch this to `false` when loader hooks are run on a separate thread.
+strictEqual(isMainThread, true);
+
+// We want to make sure that internals are not leaked on the public module:
+strictEqual(workerData, null);
+strictEqual(parentPort, null);
+
+// TODO(aduh95): switch to `"undefined"` when loader hooks are run on a separate thread.
+// We don't want `import.meta.resolve` being available from loaders
+// as the sync implementation is not compatible with calling async
+// functions on the same thread.
+strictEqual(typeof import.meta.resolve, 'function');

test/fixtures/es-module-loaders/never-settling-resolve-step/import.meta.never-resolve.mjs

@@ -0,0 +1,5 @@
+console.log('should be output');
+
+await import.meta.resolve('never-settle-resolve');
+
+console.log('should not be output');