nodejs
diff --git a/Collapse file
‎lib/internal/test_runner/mock/mock_timers.js‎
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+3Lines changed: 3 additions & 0 deletions b/Collapse file
‎lib/internal/test_runner/mock/mock_timers.js‎
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+3Lines changed: 3 additions & 0 deletions
diff --git a/Collapse file
‎test/parallel/test-runner-mock-timers-date.js‎
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+7Lines changed: 7 additions & 0 deletions b/Collapse file
‎test/parallel/test-runner-mock-timers-date.js‎
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+7Lines changed: 7 additions & 0 deletions
@@ -335,6 +335,9 @@ 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
 
@@ -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' });
+    });
+  });
 });