react-testing-library/src/__tests__/multi-base.js

import * as React from 'react'
import {render} from '../'

// these are created once per test suite and reused for each case
let treeA, treeB
beforeAll(() => {
  treeA = document.createElement('div')
  treeB = document.createElement('div')
  document.body.appendChild(treeA)
  document.body.appendChild(treeB)
})

afterAll(() => {
  treeA.parentNode.removeChild(treeA)
  treeB.parentNode.removeChild(treeB)
})

test('baseElement isolates trees from one another', () => {
  const {getByText: getByTextInA} = render(<div>Jekyll</div>, {
    baseElement: treeA,
  })
  const {getByText: getByTextInB} = render(<div>Hyde</div>, {
    baseElement: treeB,
  })

  expect(() => getByTextInA('Jekyll')).not.toThrow(
    'Unable to find an element with the text: Jekyll.',
  )
  expect(() => getByTextInB('Jekyll')).toThrow(
    'Unable to find an element with the text: Jekyll.',
  )

  expect(() => getByTextInA('Hyde')).toThrow(
    'Unable to find an element with the text: Hyde.',
  )
  expect(() => getByTextInB('Hyde')).not.toThrow(
    'Unable to find an element with the text: Hyde.',
  )
})

// https://github.com/testing-library/eslint-plugin-testing-library/issues/188
/*
eslint
  testing-library/prefer-screen-queries: "off",
*/