Jest测试中对比两个JS对象时如何忽略深层嵌套的uuid属性

以下三种方案可根据你的使用场景选择：

方案1：递归清理uuid后直接对比 #

通用度最高，不限制对象结构，先移除所有层级的uuid属性后再做全等对比：

// 递归移除对象所有层级的uuid属性
const removeUUIDs = (obj) => {
  if (Array.isArray(obj)) {
    return obj.map(item => removeUUIDs(item));
  }
  if (obj !== null && typeof obj === 'object') {
    const newObj = {};
    for (const key in obj) {
      if (key !== 'uuid') {
        newObj[key] = removeUUIDs(obj[key]);
      }
    }
    return newObj;
  }
  return obj;
};

// 测试用例
test('两个对象除uuid外完全相等', () => {
  const object1 = { uuid: '5435443', name: 'xxx', branches: [{ uuid: '643643', children: [{ uuid: '65654' }] }] };
  const object2 = { uuid: '7657657', name: 'xxx', branches: [{ uuid: '443444', children: [{ uuid: '09809' }] }] };

  expect(removeUUIDs(object1)).toEqual(removeUUIDs(object2));
});

方案2：使用Jest不对称匹配器 #

适合明确知道对象结构的场景，不需要额外编写工具函数，直接用Jest自带的匹配器规则实现：

test('两个对象除uuid外完全相等', () => {
  const object1 = { uuid: '5435443', name: 'xxx', branches: [{ uuid: '643643', children: [{ uuid: '65654' }] }] };
  const object2 = { uuid: '7657657', name: 'xxx', branches: [{ uuid: '443444', children: [{ uuid: '09809' }] }] };

  // 匹配规则中不需要声明uuid字段，Jest会自动忽略未声明的字段做匹配
  const matchRule = expect.objectContaining({
    name: 'xxx',
    branches: expect.arrayContaining([
      expect.objectContaining({
        children: expect.arrayContaining([
          expect.objectContaining({})
        ])
      })
    ])
  });

  expect(object1).toEqual(matchRule);
  expect(object2).toEqual(matchRule);
});

方案3：自定义Jest匹配器复用逻辑 #

如果项目中频繁需要做忽略uuid的对比，可以封装为全局自定义匹配器，减少重复代码：

// 可放在jest.setup.js中全局注册，复用方案1的removeUUIDs工具函数
expect.extend({
  toEqualExceptUUID(received, expected) {
    const cleanReceived = removeUUIDs(received);
    const cleanExpected = removeUUIDs(expected);
    const pass = this.equals(cleanReceived, cleanExpected);
    
    if (pass) {
      return {
        message: () => `预期两个对象除uuid外不相等，但实际相等`,
        pass: true
      };
    } else {
      return {
        message: () => `预期两个对象除uuid外相等，差异如下：\n${this.utils.diff(cleanReceived, cleanExpected)}`,
        pass: false
      };
    }
  }
});

// 测试用例中直接调用
test('两个对象除uuid外完全相等', () => {
  const object1 = { uuid: '5435443', name: 'xxx', branches: [{ uuid: '643643', children: [{ uuid: '65654' }] }] };
  const object2 = { uuid: '7657657', name: 'xxx', branches: [{ uuid: '443444', children: [{ uuid: '09809' }] }] };

  expect(object1).toEqualExceptUUID(object2);
});

内容的提问来源于stack exchange，提问作者fullstack