From 52a34efe2fea861d35e5865695eee7d2f437b5c0 Mon Sep 17 00:00:00 2001
From: RedYetiDev <38299977+RedYetiDev@users.noreply.github.com>
Date: Thu, 14 Nov 2024 18:01:11 -0500
Subject: [PATCH] test_runner: error on mocking an already mocked date

Fixes #55849
---
 lib/internal/test_runner/mock/mock_timers.js  | 3 +++
 test/parallel/test-runner-mock-timers-date.js | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/lib/internal/test_runner/mock/mock_timers.js b/lib/internal/test_runner/mock/mock_timers.js
index 66375c6688e038..c479f69ed0ddff 100644
--- a/lib/internal/test_runner/mock/mock_timers.js
+++ b/lib/internal/test_runner/mock/mock_timers.js
@@ -328,6 +328,9 @@ class MockTimers {
   #createDate() {
     kMock ??= Symbol('MockTimers');
     const NativeDateConstructor = this.#nativeDateDescriptor.value;
+    if (NativeDateConstructor.isMock) {
+      throw new ERR_INVALID_STATE('Date is already being mocked!');
+    }
     /**
      * Function to mock the Date constructor, treats cases as per ECMA-262
      * and returns a Date object with a mocked implementation
diff --git a/test/parallel/test-runner-mock-timers-date.js b/test/parallel/test-runner-mock-timers-date.js
index ebd1e430be803f..7cee835eccaba3 100644
--- a/test/parallel/test-runner-mock-timers-date.js
+++ b/test/parallel/test-runner-mock-timers-date.js
@@ -117,4 +117,11 @@ describe('Mock Timers Date Test Suite', () => {
     assert.strictEqual(fn.mock.callCount(), 0);
     clearTimeout(id);
   });
+
+  it((t) => {
+    t.mock.timers.enable();
+    t.test('should throw when a already-mocked Date is mocked', (t2) => {
+      assert.throws(() => t2.mock.timers.enable(), { code: 'ERR_INVALID_STATE' });
+    });
+  });
 });