test(shared/hooks): 抽取 transition 的 useChildren 为公共 hook useValueWith…

…Prev

packages/shared/src/hooks/__tests__/useValueWithPrev.test.ts

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+import { renderHook, act } from '@testing-library/react';
+import { useValueWithPrev } from '@pkg/shared';
+import { useState } from 'react';
+
+describe('useValueWithPrev', () => {
+  it('should work', () => {
+    let values: any[] = [];
+    const hook = renderHook(() => {
+      const [child, setChild] = useState<unknown>();
+      const children = useValueWithPrev(child);
+      values = children;
+      return [children, setChild] as const;
+    });
+
+    const [, setChild] = hook.result.current;
+
+    expect(hook.result.current[0]).toEqual([undefined, undefined]);
+    expect(hook.result.current[0]).toEqual(values);
+
+    act(() => setChild(true));
+    expect(hook.result.current[0]).toEqual([true, undefined]);
+    expect(hook.result.current[0]).toEqual(values);
+
+    // 同样的元素不会替换
+    act(() => setChild(true));
+    expect(hook.result.current[0]).toEqual([true, undefined]);
+    expect(hook.result.current[0]).toEqual(values);
+
+    act(() => setChild(false));
+    expect(hook.result.current[0]).toEqual([false, true]);
+    expect(hook.result.current[0]).toEqual(values);
+
+    act(() => setChild(false));
+    expect(hook.result.current[0]).toEqual([false, true]);
+    expect(hook.result.current[0]).toEqual(values);
+
+    act(() => setChild(false));
+    expect(hook.result.current[0]).toEqual([false, true]);
+    expect(hook.result.current[0]).toEqual(values);
+  });
+});