酶测文字包括子成分

Question

我有一个功能组件getCurrencyRate：

export const getCurrencyRate = (value1, value2) => {
  return (
    <span>
      The rate is: 
      <Sum currency={value2}>
        {value1}
      </Sum>
    </span>
  );
};

它使用来自另一个文件的Sum组件：

export const Sum = (props) => {
  const { children, currency } = props;
  return (
    <span>
      {children} {currency}
    </span>
  );
};

我想测试getCurrencyRate组件。我是这样的：

  it('should return correct value', () => {
    const correctResult = <span>The rate is: <Sum currency='USD'>500</Sum></span>;
    const result = shallow(getCurrencyRate(500, 'USD'));
    expect(result.text()).toEqual(correctResult);
  });

并得到一个错误：

Expected value to equal:
  <span>The rate is: <Sum currency='USD'>500</Sum></span>an>
Received:
  "The rate is: <Sum />"

我该如何解决？