@jest library/jest-dom未加载

Question

我正在尝试将React Testing Library引入到Create React App项目中，我遇到了一个奇怪的问题。对于我的一个测试，我需要使用jest-dom，但是我似乎不能成功地导入它。

我已经yarn add了它，想不起来我错过了什么步骤。expect.extend失败了，因为它的toHaveStyle未定义。

下面是我的测试文件，缩小到最小：

import React from 'react';
import {render, screen} from '@testing-library/react';

import {toHaveStyle} from '@testing-library/jest-dom';
import '@testing-library/jest-dom/extend-expect';
//expect.extend({toHaveStyle});

it('is confusing me', () => {
  // (Using `toBe(42) as an ersatz `console.log`)
  expect([Object.keys(require('@testing-library/jest-dom')), Object.keys(require('@testing-library/react')), toHaveClass]).toBe(42);
});

输出为：

  Expected: 42
    Received: [[], ["render", "cleanup", "fireEvent", ...], undefined]

下面是yarn.lock的相关部分：

"@testing-library/jest-dom@^5.7.0":
  version "5.7.0"
  resolved "https://registry.yarnpkg.com/@testing-library/jest-dom/-/jest-dom-5.7.0.tgz#b2e2acb4c088a293d52ba2cd1674b526282a2f87"
  integrity sha512-ZV0OtBXmTDEDxrIbqJXiOcXCZ6aIMpmDlmfHj0hGNsSuQ/nX0qPAs9HWmCzXvPfTrhufTiH2nJLvDJu/LgHzwQ==
  dependencies:
    "@babel/runtime" "^7.9.2"
    "@types/testing-library__jest-dom" "^5.0.2"
    chalk "^3.0.0"
    css "^2.2.4"
    css.escape "^1.5.1"
    jest-diff "^25.1.0"
    jest-matcher-utils "^25.1.0"
    lodash "^4.17.15"
    redent "^3.0.0"

"@testing-library/react@^10.0.4":
  version "10.0.4"
  resolved "https://registry.yarnpkg.com/@testing-library/react/-/react-10.0.4.tgz#8e0e299cd91acc626d81ed8489fdc13df864c31d"
  integrity sha512-2e1B5debfuiIGbvUuiSXybskuh7ZTVJDDvG/IxlzLOY9Co/mKFj9hIklAe2nGZYcOUxFaiqWrRZ9vCVGzJfRlQ==
  dependencies:
    "@babel/runtime" "^7.9.6"
    "@testing-library/dom" "^7.2.2"
    "@types/testing-library__react" "^10.0.1"

Answer 1

下面是我如何使用这个伟大的库：

// in test file
import '@testing-library/jest-dom/extend-expect';

[...]

// then matchers are available in tests
expect(rtl.getByText('text').toHaveClass('some-class');

我的进口与你的略有不同，我不能准确地说出你的进口出了什么问题，但我是这样做的。

祝你好运！

Answer 2

好了，jest-dom文档已经更新了。

import {toHaveStyle} from '@testing-library/jest-dom';

将不再起作用。相反，

import {toHaveStyle} from '@testing-library/jest-dom/matchers'

有关参考信息，请参阅jest-dom