next.js/test/development/basic/styled-components/styled-components.test.ts

import webdriver from 'next-webdriver'
import { nextTestSetup } from 'e2e-utils'
import { fetchViaHTTP, renderViaHTTP } from 'next-test-utils'

describe('styled-components SWC transform', () => {
  const { next } = nextTestSetup({
    files: __dirname,
    dependencies: {
      'styled-components': '6.1.16',
    },
  })
  async function matchLogs$(browser) {
    let foundLog = false

    const browserLogs = await browser.log()

    browserLogs.forEach((log) => {
      if (log.message.includes('Warning: Prop `%s` did not match.')) {
        foundLog = true
      }
    })
    return foundLog
  }

  it('should not have hydration mismatch with styled-components transform enabled', async () => {
    let browser
    try {
      browser = await webdriver(next.url, '/')

      // Compile /_error
      await fetchViaHTTP(next.url, '/404')

      // Try 4 times to be sure there is no mismatch
      expect(await matchLogs$(browser)).toBe(false)
      await browser.refresh()
      expect(await matchLogs$(browser)).toBe(false)
      await browser.refresh()
      expect(await matchLogs$(browser)).toBe(false)
      await browser.refresh()
      expect(await matchLogs$(browser)).toBe(false)
    } finally {
      if (browser) {
        await browser.close()
      }
    }
  })

  it('should render the page with correct styles', async () => {
    const browser = await webdriver(next.url, '/')

    expect(
      await browser.eval(
        `window.getComputedStyle(document.querySelector('#btn')).color`
      )
    ).toBe('rgb(255, 255, 255)')
    expect(
      await browser.eval(
        `window.getComputedStyle(document.querySelector('#wrap-div')).color`
      )
    ).toBe('rgb(0, 0, 0)')
  })

  it('should enable the display name transform by default', async () => {
    // make sure the index chunk gets generated
    const html = await next.render('/')
    expect(html).toContain('pages__Button')
  })

  it('should contain styles in initial HTML', async () => {
    const html = await renderViaHTTP(next.url, '/')
    expect(html).toContain('background:transparent')
    expect(html).toContain('color:white')
  })

  it('should only render once on the server per request', async () => {
    const outputs = []
    next.on('stdout', (args) => {
      outputs.push(args)
    })
    await renderViaHTTP(next.url, '/')
    expect(
      outputs.filter((output) => output.trim() === '__render__').length
    ).toBe(1)
  })
})