test_runner: set mock timer's interval undefined

hotpineapple · richardlau · commit 76bf6b908dec · 2025-09-20T06:15:48.000Z
prevent adding timer to execution queue if clearInterval() called PR-URL: #59479 Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
diff --git a/lib/internal/test_runner/mock/mock_timers.js b/lib/internal/test_runner/mock/mock_timers.js
@@ -328,6 +328,7 @@ class MockTimers {
     if (timer?.priorityQueuePosition !== undefined) {
       this.#executionQueue.removeAt(timer.priorityQueuePosition);
       timer.priorityQueuePosition = undefined;
+      timer.interval = undefined;
     }
   }
 
diff --git a/test/parallel/test-runner-mock-timers.js b/test/parallel/test-runner-mock-timers.js
@@ -201,6 +201,27 @@ describe('Mock Timers Test Suite', () => {
         // Should not throw
       });
     });
+
+    it('interval cleared inside callback should only fire once', (t) => {
+      t.mock.timers.enable();
+      const calls = [];
+
+      setInterval(() => {
+        calls.push('foo');
+      }, 10);
+      const timerId = setInterval(() => {
+        calls.push('bar');
+        clearInterval(timerId);
+      }, 10);
+
+      t.mock.timers.tick(10);
+      t.mock.timers.tick(10);
+
+      assert.deepStrictEqual(
+        calls,
+        ['foo', 'bar', 'foo'],
+      );
+    });
   });
 
   describe('globals/timers', () => {
