[Tests] Add unit tests for OpenTelemetry throttle utility

packages/cli-kit/src/public/node/vendor/otel-js/utils/throttle.test.ts

@@ -0,0 +1,100 @@
+import {throttle} from './throttle.js'
+import {describe, expect, test, vi} from 'vitest'
+
+describe('throttle', () => {
+  test('executes immediately on leading edge by default', () => {
+    vi.useFakeTimers()
+    try {
+      const func = vi.fn((...args: unknown[]) => (args[0] as number) * 2)
+      const throttled = throttle(func, 100)
+
+      const result = throttled(5)
+      expect(func).toHaveBeenCalledTimes(1)
+      expect(func).toHaveBeenCalledWith(5)
+      expect(result).toBe(10)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  test('throttles calls within wait period and executes latest call on trailing edge', () => {
+    vi.useFakeTimers()
+    try {
+      const func = vi.fn((...args: unknown[]) => (args[0] as number) * 2)
+      const throttled = throttle(func, 100)
+
+      throttled(1)
+      expect(func).toHaveBeenCalledTimes(1)
+      expect(func).toHaveBeenCalledWith(1)
+
+      throttled(2)
+      throttled(3)
+      expect(func).toHaveBeenCalledTimes(1)
+
+      vi.advanceTimersByTime(100)
+      expect(func).toHaveBeenCalledTimes(2)
+      expect(func).toHaveBeenCalledWith(3)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  test('respects leading: false option by suppressing immediate execution', () => {
+    vi.useFakeTimers()
+    try {
+      const func = vi.fn((...args: unknown[]) => (args[0] as number) * 2)
+      const throttled = throttle(func, 100, {leading: false})
+
+      throttled(1)
+      expect(func).not.toHaveBeenCalled()
+
+      vi.advanceTimersByTime(100)
+      expect(func).toHaveBeenCalledTimes(1)
+      expect(func).toHaveBeenCalledWith(1)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  test('respects trailing: false option by disabling trailing edge execution', () => {
+    vi.useFakeTimers()
+    try {
+      const func = vi.fn((...args: unknown[]) => (args[0] as number) * 2)
+      const throttled = throttle(func, 100, {trailing: false})
+
+      throttled(1)
+      expect(func).toHaveBeenCalledTimes(1)
+      expect(func).toHaveBeenCalledWith(1)
+
+      throttled(2)
+      vi.advanceTimersByTime(100)
+      expect(func).toHaveBeenCalledTimes(1)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  test('swallows rejected promise errors on trailing edge execution to prevent unhandled rejections', async () => {
+    vi.useFakeTimers()
+    try {
+      const func = vi.fn((...args: unknown[]) => Promise.reject(new Error(`Failed ${args[0] as number}`)))
+      const throttled = throttle(func, 100)
+
+      // Leading call - catch its rejection
+      const p1 = throttled(1)
+      await expect(p1).rejects.toThrow('Failed 1')
+
+      // Trailing call
+      throttled(2)
+
+      // Advance timers to trigger trailing execution
+      vi.advanceTimersByTime(100)
+
+      // Expect function called for trailing execution without unhandled promise rejection
+      expect(func).toHaveBeenCalledTimes(2)
+      expect(func).toHaveBeenCalledWith(2)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+})