test_runner: add exports option for module mocks

Add options.exports support in mock.module() and normalize option

shapes through a shared exports path.

Keep defaultExport and namedExports as aliases, emit runtime

deprecation warnings for legacy options, and update docs and tests,

including output fixtures and coverage snapshots.

Refs: #58443
PR-URL: #61727
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com>
Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>
Reviewed-By: Chemi Atlow <chemi@atlow.co.il>

Author: Han5991

doc/api/test.md

@@ -2477,16 +2477,32 @@ changes:
     generates a new mock module. If `true`, subsequent calls will return the same
     module mock, and the mock module is inserted into the CommonJS cache.
     **Default:** false.
+  * `exports` {Object} Optional mocked exports. The `default` property, if
+    provided, is used as the mocked module's default export. All other own
+    enumerable properties are used as named exports.
+    **This option cannot be used with `defaultExport` or `namedExports`.**
+    * If the mock is a CommonJS or builtin module, `exports.default` is used as
+      the value of `module.exports`.
+    * If `exports.default` is not provided for a CommonJS or builtin mock,
+      `module.exports` defaults to an empty object.
+    * If named exports are provided with a non-object default export, the mock
+      throws an exception when used as a CommonJS or builtin module.
   * `defaultExport` {any} An optional value used as the mocked module's default
     export. If this value is not provided, ESM mocks do not include a default
     export. If the mock is a CommonJS or builtin module, this setting is used as
     the value of `module.exports`. If this value is not provided, CJS and builtin
     mocks use an empty object as the value of `module.exports`.
+    **This option cannot be used with `options.exports`.**
+    This option is deprecated and will be removed in a later version.
+    Prefer `options.exports.default`.
   * `namedExports` {Object} An optional object whose keys and values are used to
     create the named exports of the mock module. If the mock is a CommonJS or
     builtin module, these values are copied onto `module.exports`. Therefore, if a
     mock is created with both named exports and a non-object default export, the
     mock will throw an exception when used as a CJS or builtin module.
+    **This option cannot be used with `options.exports`.**
+    This option is deprecated and will be removed in a later version.
+    Prefer `options.exports`.
 * Returns: {MockModuleContext} An object that can be used to manipulate the mock.
 
 This function is used to mock the exports of ECMAScript modules, CommonJS modules, JSON modules, and
@@ -2503,10 +2519,10 @@ The following example demonstrates how a mock is created for a module.
 
 ```js
 test('mocks a builtin module in both module systems', async (t) => {
-  // Create a mock of 'node:readline' with a named export named 'fn', which
+  // Create a mock of 'node:readline' with a named export named 'foo', which
   // does not exist in the original 'node:readline' module.
   const mock = t.mock.module('node:readline', {
-    namedExports: { fn() { return 42; } },
+    exports: { foo: () => 42 },
   });
 
   let esmImpl = await import('node:readline');

lib/internal/test_runner/mock/loader.js

@@ -113,10 +113,10 @@ function defaultExportSource(useESM, hasDefaultExport) {
   if (!hasDefaultExport) {
     return '';
   } else if (useESM) {
-    return 'export default $__exports.defaultExport;';
+    return 'export default $__exports.moduleExports.default;';
   }
 
-  return 'module.exports = $__exports.defaultExport;';
+  return 'module.exports = $__exports.moduleExports.default;';
 }
 
 function namedExportsSource(useESM, exportNames) {
@@ -134,9 +134,9 @@ if (module.exports === null || typeof module.exports !== 'object') {
     const name = exportNames[i];
 
     if (useESM) {
-      source += `export let ${name} = $__exports.namedExports[${JSONStringify(name)}];\n`;
+      source += `export let ${name} = $__exports.moduleExports[${JSONStringify(name)}];\n`;
     } else {
-      source += `module.exports[${JSONStringify(name)}] = $__exports.namedExports[${JSONStringify(name)}];\n`;
+      source += `module.exports[${JSONStringify(name)}] = $__exports.moduleExports[${JSONStringify(name)}];\n`;
     }
   }
 

lib/internal/test_runner/mock/mock.js

@@ -1,10 +1,12 @@
 'use strict';
 const