Move process.env mock test to test/parallel and fix restore usage

Author: Sakina Farukh Ahemad

test/parallel/test-env-mock-process-env.js

@@ -1,32 +1,12 @@
 'use strict';
-
-// Flags: --expose-internals
 require('../common');
+const { test, mock } = require('node:test');
 const assert = require('assert');
 
-// This test verifies mocking and restoring process.env.TEST_ENV
-
-const hadOriginal = Object.prototype.hasOwnProperty.call(process.env, 'TEST_ENV');
-const original = process.env.TEST_ENV;
-
-// Mock environment variable
-process.env.TEST_ENV = 'mocked';
-assert.strictEqual(process.env.TEST_ENV, 'mocked');
-console.log('Mocked process.env.TEST_ENV successfully');
-
-// Restore original variable
-if (hadOriginal) {
-  process.env.TEST_ENV = original;
-} else {
-  delete process.env.TEST_ENV;
-}
-
-//  Validation
-if (hadOriginal) {
-  assert.strictEqual(process.env.TEST_ENV, original);
-} else {
-  assert.ok(!('TEST_ENV' in process.env));
-}
-
-console.log('Restored original process.env.TEST_ENV');
+test('Testing mock.property() with process.env', () => {
+  console.log('Testing mock.property() with process.env...');
 
+  mock.property(process, 'env', { TEST_ENV: 'mocked' });
+  assert.strictEqual(process.env.TEST_ENV, 'mocked');
+  console.log('Mocked process.env.TEST_ENV successfully');
+});