Reactjs 反应&；酶：为什么不是'；在每一次工作之前你都做了什么？

我正在编写第一个React测试，遇到了一个问题，我的

beforeach

语句都不起作用。这是我的测试文件：

import React from 'react';
import { shallow } from 'enzyme';
import Home from '../components/Home';
import IntroText from '../components/IntroText';
import Form from '../components/Form';

describe('<Home />', () => {
  beforeEach(() => {
    const wrapper = shallow(<Home />);
  });

  it('renders the IntroText component', () => {
    expect(wrapper.find(IntroText).length).toBe(1);
  });

  it('renders the Form component', () => {
    expect(wrapper.find(Form).length).toBe(1);
  });
});

当测试运行时，我遇到此错误：

ReferenceError: wrapper is not defined

---

我遗漏了什么？

如果在每个作用域之前定义了

范围内的包装常量，请将其移到外部，如下所示：

import React from 'react';
import { shallow } from 'enzyme';
import Home from '../components/Home';
import IntroText from '../components/IntroText';
import Form from '../components/Form';

describe('<Home />', () => {
  let wrapper;
  beforeEach(() => {
    wrapper = shallow(<Home />);
  });

  it('renders the IntroText component', () => {
    expect(wrapper.find(IntroText).length).toBe(1);
  });

  it('renders the Form component', () => {
    expect(wrapper.find(Form).length).toBe(1);
  });
});

谢谢，非常感谢！这是范围的经典示例！如果您仍然没有定义：-我在测试中需要的对象上尝试了这种方法（它是在beforeach（）中定义的）&然后在测试语句中引用/使用，但仍然没有定义。即使使用
this.myobject
approach^^。我阅读了Jest文档，看起来它们似乎在导入下方的全局/顶级范围中定义了对象本身，然后在
beforeach（）中指定它是什么
然后可以在测试语句中使用它。
import React from 'react';
import { shallow } from 'enzyme';
import Home from '../components/Home';
import IntroText from '../components/IntroText';
import Form from '../components/Form';

describe('<Home />', () => {
  let wrapper;
  beforeEach(() => {
    wrapper = shallow(<Home />);
  });

  it('renders the IntroText component', () => {
    expect(wrapper.find(IntroText).length).toBe(1);
  });

  it('renders the Form component', () => {
    expect(wrapper.find(Form).length).toBe(1);
  });
});

import React from 'react';
import { shallow } from 'enzyme';
import Home from '../components/Home';
import IntroText from '../components/IntroText';
import Form from '../components/Form';

describe('<Home />', function() {
  beforeEach(function() {
    this.wrapper = shallow(<Home />);
  });

  it('renders the IntroText component', function() {
    expect(this.wrapper.find(IntroText).length).toBe(1);
  });

  it('renders the Form component', function() {
    expect(this.wrapper.find(Form).length).toBe(1);
  });
});