test: add VFS bare specifier ESM resolution test

Add a test that exercises ESM bare specifier resolution (e.g.,
import 'my-vfs-pkg') from a node_modules directory inside VFS.
This ensures the internalModuleStat wrapper and package.json
reader hooks correctly handle package resolution for virtual
file system mounts.

Author: mcollina

test/parallel/test-vfs-import.mjs

@@ -108,3 +108,30 @@ import vfs from 'node:vfs';
 
   myVfs.unmount();
 }
+
+// Test ESM bare specifier resolution from VFS node_modules.
+// This sets up a proper node_modules structure inside VFS and imports
+// using a bare specifier (e.g., import 'my-vfs-pkg') instead of an
+// absolute path. This exercises the ESM default resolver's
+// internalModuleStat and getPackageJSONURL code paths.
+{
+  const myVfs = vfs.create();
+  myVfs.mkdirSync('/app/node_modules/my-vfs-pkg', { recursive: true });
+  myVfs.writeFileSync('/app/node_modules/my-vfs-pkg/package.json', JSON.stringify({
+    name: 'my-vfs-pkg',
+    type: 'module',
+    exports: { '.': './index.mjs' },
+  }));
+  myVfs.writeFileSync('/app/node_modules/my-vfs-pkg/index.mjs',
+    'export const fromVfs = true;');
+  // The importing module must also live inside the VFS mount so that
+  // node_modules resolution walks upward from a VFS path.
+  myVfs.writeFileSync('/app/entry.mjs',
+    "export { fromVfs } from 'my-vfs-pkg';");
+  myVfs.mount('/virtual9');
+
+  const { fromVfs } = await import('/virtual9/app/entry.mjs');
+  assert.strictEqual(fromVfs, true);
+
+  myVfs.unmount();
+}