diff --git a/Timing-Functions/test/IntervalTimer.test.js b/Timing-Functions/test/IntervalTimer.test.js
new file mode 100644
index 0000000000..4e588cc1c2
--- /dev/null
+++ b/Timing-Functions/test/IntervalTimer.test.js
@@ -0,0 +1,288 @@
+import { IntervalTimer, ExampleIntervalTimer } from '../IntervalTimer'
+
+describe('IntervalTimer', () => {
+  let timerInstances = []
+
+  // Reset singleton instance before each test
+  beforeEach(() => {
+    // Clear any existing timer instances
+    timerInstances.forEach((timer) => {
+      if (timer && timer.timer) {
+        clearInterval(timer.timer)
+      }
+      if (timer && timer.instance) {
+        timer.instance = null
+      }
+    })
+    timerInstances = []
+  })
+
+  afterEach(() => {
+    // Clean up any running timers
+    timerInstances.forEach((timer) => {
+      if (timer && timer.timer) {
+        clearInterval(timer.timer)
+      }
+    })
+  })
+
+  describe('Constructor', () => {
+    it('should create an instance with default parameters', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      expect(timer).toBeInstanceOf(IntervalTimer)
+      expect(timer.interval).toBe(10)
+      expect(typeof timer.callBack).toBe('function')
+    })
+
+    it('should create an instance with custom interval', () => {
+      const timer = new IntervalTimer(50)
+      timerInstances.push(timer)
+      expect(timer.interval).toBe(50)
+    })
+
+    it('should create an instance with custom callback', () => {
+      const mockCallback = vi.fn()
+      const timer = new IntervalTimer(10, mockCallback)
+      timerInstances.push(timer)
+      expect(timer.callBack).toBe(mockCallback)
+    })
+
+    it('should set instance property on creation', () => {
+      const timer1 = new IntervalTimer(20)
+      timerInstances.push(timer1)
+      const timer2 = new IntervalTimer(30)
+      timerInstances.push(timer2)
+
+      // The implementation sets this.instance = this for each instance
+      // Note: This is not a true singleton pattern as each new instance creates a separate object
+      expect(timer1.instance).toBe(timer1)
+      expect(timer2.instance).toBe(timer2)
+      expect(timer1.interval).toBe(20)
+      expect(timer2.interval).toBe(30)
+    })
+  })
+
+  describe('startTimer', () => {
+    it('should start the timer interval', async () => {
+      let callbackCalled = false
+      const mockCallback = vi.fn(() => {
+        callbackCalled = true
+      })
+      const timer = new IntervalTimer(10, mockCallback)
+      timerInstances.push(timer)
+
+      timer.startTimer()
+
+      // Wait for callback to be called - use a longer timeout to ensure it fires
+      // In Node.js, the minimum delay might be larger, so we wait longer
+      await new Promise((resolve) => setTimeout(resolve, 100))
+
+      // Verify timer is running
+      expect(timer.timer).toBeDefined()
+      // Callback should have been called at least once
+      expect(callbackCalled || mockCallback.mock.calls.length > 0).toBe(true)
+      clearInterval(timer.timer)
+    })
+
+    it('should store the timer ID', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      expect(timer.timer).toBeDefined()
+      // In Node.js, setInterval returns a Timeout object, not a number
+      // In browsers, it returns a number. Both are valid.
+      expect(
+        typeof timer.timer === 'number' || typeof timer.timer === 'object'
+      ).toBe(true)
+
+      clearInterval(timer.timer)
+    })
+  })
+
+  describe('getElapsedTime', () => {
+    it('should return elapsed time with default offset', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      // getElapsedTime uses timer ID arithmetic which may not work as expected
+      // but we test the actual behavior
+      const elapsed = timer.getElapsedTime()
+
+      expect(typeof elapsed).toBe('number')
+
+      clearInterval(timer.timer)
+    })
+
+    it('should subtract offset from elapsed time', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      const offset = 100
+      const elapsed = timer.getElapsedTime(offset)
+
+      expect(typeof elapsed).toBe('number')
+
+      clearInterval(timer.timer)
+    })
+
+    it('should update prevInterval on each call', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      const prevIntervalBefore = timer.prevInterval
+      timer.getElapsedTime()
+      const prevIntervalAfter = timer.prevInterval
+
+      expect(prevIntervalAfter).not.toBe(prevIntervalBefore)
+
+      clearInterval(timer.timer)
+    })
+  })
+
+  describe('getRunTime', () => {
+    it('should return the timer ID', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      const runTime = timer.getRunTime()
+
+      expect(runTime).toBe(timer.timer)
+      // In Node.js, setInterval returns a Timeout object, not a number
+      // In browsers, it returns a number. Both are valid.
+      expect(typeof runTime === 'number' || typeof runTime === 'object').toBe(
+        true
+      )
+
+      clearInterval(timer.timer)
+    })
+  })
+
+  describe('resetTimer', () => {
+    it('should clear the timer interval', async () => {
+      const mockCallback = vi.fn()
+      const timer = new IntervalTimer(10, mockCallback)
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      timer.resetTimer()
+
+      // Verify timer was cleared - callback should not be called after reset
+      mockCallback.mockClear()
+
+      // Wait a bit to ensure no more callbacks are called
+      await new Promise((resolve) => setTimeout(resolve, 30))
+
+      expect(mockCallback).not.toHaveBeenCalled()
+    })
+
+    it('should reset the callback to empty function', () => {
+      const mockCallback = vi.fn()
+      const timer = new IntervalTimer(10, mockCallback)
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      timer.resetTimer()
+
+      expect(timer.callBack).not.toBe(mockCallback)
+      expect(typeof timer.callBack).toBe('function')
+    })
+
+    it('should return elapsed time', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      const elapsed = timer.resetTimer()
+
+      expect(typeof elapsed).toBe('number')
+    })
+
+    it('should allow timer to be started again after reset', async () => {
+      let callbackCalled = false
+      const mockCallback = vi.fn(() => {
+        callbackCalled = true
+      })
+      const timer = new IntervalTimer(10, mockCallback)
+      timerInstances.push(timer)
+
+      timer.startTimer()
+      timer.resetTimer()
+
+      // Reset the flag
+      callbackCalled = false
+      mockCallback.mockClear()
+
+      // Set new callback and start again
+      timer.callBack = mockCallback
+      timer.startTimer()
+
+      // Wait for callback to be called - use a longer timeout to ensure it fires
+      await new Promise((resolve) => setTimeout(resolve, 100))
+
+      expect(timer.timer).toBeDefined()
+      // Callback should have been called at least once
+      expect(callbackCalled || mockCallback.mock.calls.length > 0).toBe(true)
+      clearInterval(timer.timer)
+    })
+  })
+
+  describe('Integration tests', () => {
+    it('should work with typical usage pattern', () => {
+      const timer = new IntervalTimer(10)
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      // Simulate initialization
+      const initOffset = timer.getRunTime()
+
+      // Simulate some work
+      const elapsed = timer.getElapsedTime(initOffset)
+
+      expect(typeof elapsed).toBe('number')
+
+      // Reset
+      const finalElapsed = timer.resetTimer()
+      expect(typeof finalElapsed).toBe('number')
+    })
+
+    it('should handle multiple getElapsedTime calls', () => {
+      const timer = new IntervalTimer()
+      timerInstances.push(timer)
+      timer.startTimer()
+
+      const elapsed1 = timer.getElapsedTime()
+      const elapsed2 = timer.getElapsedTime()
+      const elapsed3 = timer.getElapsedTime()
+
+      expect(typeof elapsed1).toBe('number')
+      expect(typeof elapsed2).toBe('number')
+      expect(typeof elapsed3).toBe('number')
+
+      clearInterval(timer.timer)
+    })
+  })
+})
+
+describe('ExampleIntervalTimer', () => {
+  it('should execute without errors', () => {
+    const mockOutput = vi.fn()
+
+    expect(() => {
+      ExampleIntervalTimer(mockOutput)
+    }).not.toThrow()
+
+    // Clean up - the ExampleIntervalTimer creates a timer instance
+    // We need to access it through the singleton pattern
+    const timer = new IntervalTimer()
+    if (timer.instance && timer.instance.timer) {
+      clearInterval(timer.instance.timer)
+      timer.instance.instance = null
+    }
+  })
+})