squash: extend test

Author: LiviaMedeiros

test/parallel/test-common-can-not-mutate-object-deep.mjs

@@ -1,5 +1,6 @@
 import { canNotMutateObjectDeep } from '../common/index.mjs';
 import assert from 'node:assert';
+import { promisify } from 'node:util';
 
 // Test common.canNotMutateObjectDeep()
 
@@ -197,3 +198,28 @@ function setPrototypeOfQuux(root) {
   assert.deepStrictEqual(canNotMutateObjectDeep({ target }), { target });
   assert.deepStrictEqual(canNotMutateObjectDeep([ target ]), [ target ]);
 });
+
+// Test that passed functions keep working correctly
+{
+  const fn = () => 'blep';
+  fn.foo = {};
+  const fnImmutableView = canNotMutateObjectDeep(fn);
+  assert.deepStrictEqual(fnImmutableView, fn);
+
+  // The function works
+  assert.strictEqual(fn(), 'blep');
+  assert.strictEqual(fnImmutableView(), 'blep');
+
+  // The original function is not deeply frozen
+  fn.foo.bar = 'baz';
+  assert.strictEqual(fn.foo.bar, 'baz');
+  assert.strictEqual(fnImmutableView.foo.bar, 'baz');
+
+  // The original function is not frozen
+  fn.qux = 'quux';
+  assert.strictEqual(fn.qux, 'quux');
+  assert.strictEqual(fnImmutableView.qux, 'quux');
+
+  // Redefining util.promisify.custom also works
+  await promisify(promisify(fn))();
+}