[tests]: useArrayReduce described

hooks/Array/useArrayReduce/__tests__/useArrayReduce.test.ts

@@ -0,0 +1,68 @@
+import { renderHook } from '@testing-library/react'
+import { useArrayReduce } from '../useArrayReduce'
+
+type Item = {
+  value: number
+}
+
+const sumReducer = (accumulator: number, current: Item) => {
+  return accumulator + current.value
+}
+
+describe('useArrayReduce', () => {
+  it('should calculate the sum correctly', () => {
+    const items: Item[] = [{ value: 1 }, { value: 2 }, { value: 3 }]
+    const { result } = renderHook(() => useArrayReduce(items, sumReducer, 0))
+
+    expect(result.current).toBe(6)
+  })
+
+  it('should return the initial value when the list is empty', () => {
+    const items: Item[] = []
+    const { result } = renderHook(() => useArrayReduce(items, sumReducer, 10))
+
+    expect(result.current).toBe(10)
+  })
+
+  it('should correctly handle a complex reducer', () => {
+    const items: Item[] = [{ value: 1 }, { value: 2 }, { value: 3 }]
+    const complexReducer = (accumulator: string, current: Item) => {
+      return `${accumulator}-${current.value}`
+    }
+    const { result } = renderHook(() =>
+      useArrayReduce(items, complexReducer, 'init')
+    )
+
+    expect(result.current).toBe('init-1-2-3')
+  })
+
+  it('should return a memoized result for the same input', () => {
+    const items: Item[] = [{ value: 1 }, { value: 2 }, { value: 3 }]
+    const { result, rerender } = renderHook(
+      ({ list }) => useArrayReduce(list, sumReducer, 0),
+      {
+        initialProps: { list: items },
+      }
+    )
+
+    const firstResult = result.current
+    rerender({ list: [...items] })
+
+    expect(result.current).toBe(firstResult)
+  })
+
+  it('should recompute the result when the list changes', () => {
+    const items: Item[] = [{ value: 1 }, { value: 2 }, { value: 3 }]
+    const { result, rerender } = renderHook(
+      ({ list }) => useArrayReduce(list, sumReducer, 0),
+      {
+        initialProps: { list: items },
+      }
+    )
+
+    const newItems: Item[] = [{ value: 4 }, { value: 5 }, { value: 6 }]
+    rerender({ list: newItems })
+
+    expect(result.current).toBe(15)
+  })
+})