create react app testing“未定义react”

我正在使用 react-scripts@2.1.8 具有 typescript@3.3.3 具有 jest@.23.6.0 在运行我的测试时,它们以“React is not defined”失败。

 FAIL  src/components/Button/test.tsx
  ● <Button> › renders text correctly

    ReferenceError: React is not defined

       6 |     it('renders text correctly', () => {
       7 |         const text = 'hello there i am a test'
    >  8 |         const { getByText } = customRender(<Button>{text}</Button>)
         |                                            ^
       9 |         expect(getByText(/hello there i am a test/)).toBeTruthy()
      10 |     })
      11 |     it('matches the snapshot', () => {

      at Object.it (src/components/Button/test.tsx:8:44)

  ● <Button> › matches the snapshot

    ReferenceError: React is not defined

      10 |     })
      11 |     it('matches the snapshot', () => {
    > 12 |         const { container } = customRender(<Button />)
         |                                            ^
      13 |         expect(container.firstChild).toMatchSnapshot()
      14 |     })
      15 | })

      at Object.it (src/components/Button/test.tsx:12:44)

按钮.test.tsx:

import React from 'react'
import Button from '.'
import { customRender } from '../../test-utils'

describe('<Button>', () => {
    it('renders text correctly', () => {
        const text = 'hello there i am a test'
        const { getByText } = customRender(<Button>{text}</Button>)
        expect(getByText(/hello there i am a test/)).toBeTruthy()
    })
    it('matches the snapshot', () => {
        const { container } = customRender(<Button />)
        expect(container.firstChild).toMatchSnapshot()
    })
})

还可以使用React import,比如将它从第1行移动到第3行,有时似乎可以使测试通过。这很奇怪。