如何使用 Jest 和 Enzyme 测试 React 组件

Question

使用 enzyme-example-jest Github project 我可以克隆 repo 并运行测试：

git clone https://github.com/lelandrichardson/enzyme-example-jest.git
cd enzyme-example-jest
yarn install
yarn test

但是，我取消了Foo-test.js 的第 11 行的注释：

expect(shallow(<Foo />).contains(<div className="foo" />)).toBe(true);

所以文件现在看起来像这样：

import React from 'react';
import { shallow, mount, render } from 'enzyme';

jest.dontMock('../Foo');

const Foo = require('../Foo');

describe("A suite", function() {
  it("contains spec with an expectation", function() {
    expect(true).toBe(true);
    expect(shallow(<Foo />).contains(<div className="foo" />)).toBe(true);
  });

  it("contains spec with an expectation", function() {
    //expect(shallow(<Foo />).is('.foo')).toBe(true);
  });

  it("contains spec with an expectation", function() {
    //expect(mount(<Foo />).find('.foo').length).toBe(1);
  });
});

当我运行测试时，我现在得到了这个错误：

yarn test v0.17.8
$ jest
Using Jest CLI v0.8.2, jasmine1
Running 1 test suite...Warning: React.createElement: type should not be null, undefined, boolean, or number. It should be a string (for DOM elements) or a ReactClass (for composite components).
 FAIL  src/__tests__/Foo-test.js (0.931s)
● A suite › it contains spec with an expectation
  - TypeError: Component is not a function
        at StatelessComponent.render (node_modules/react/lib/ReactCompositeComponent.js:44:10)
1 test failed, 2 tests passed (3 total in 1 test suite, run time 1.281s)
error Command failed with exit code 1.

如何成功运行此测试？

Answer 1

'Foo' 是用 ES6 类语法定义的，但在 Foo-test.js 中是 require 所必需的。使用import 将修复它。

替换这个

const Foo = require('../Foo');

有了这个

从 '../Foo' 导入 Foo；