next.js/test/production/app-dir/client-components-tree-shaking/index.test.ts

import { nextTestSetup } from 'e2e-utils'

describe('app-dir client-components-tree-shaking', () => {
  const { next, skipped } = nextTestSetup({
    files: __dirname,
    skipDeployment: true,
  })
  if (skipped) return

  it('should only include imported components 3rd party package in browser bundle with direct imports', async () => {
    const $ = await next.render$('/third-party-dep')
    const chunkContents = await Promise.all(
      $('script[src]')
        .toArray()
        .map(async (el) => {
          const href = $(el).attr('src')

          const file = await next.fetch(href).then((res) => res.text())

          return file
        })
    )

    expect(
      chunkContents.some((content) => content.includes('client-dep-bar:esm'))
    ).toBe(true)
    expect(
      chunkContents.every((content) => content.includes('client-dep-foo:esm'))
    ).toBe(false)
    expect(
      chunkContents.every((content) =>
        content.includes('client-dep-default:esm')
      )
    ).toBe(false)
  })

  it('should only include the imported identifier of CJS module in browser bundle', async () => {
    const $ = await next.render$('/cjs-dep')
    const chunkContents = await Promise.all(
      $('script[src]')
        .toArray()
        .map(async (el) => {
          const href = $(el).attr('src')

          const file = await next.fetch(href).then((res) => res.text())

          return file
        })
    )

    expect(
      chunkContents.some((content) => content.includes('cjs-client:default'))
    ).toBe(true)
    expect(
      chunkContents.every((content) => content.includes('cjs-client:foo'))
    ).toBe(false)
  })

  it('should able to resolve the client module entry with mixing rexports', async () => {
    const $ = await next.render$('/client-reexport-index')

    expect($('p').text()).toContain('client:mod-export-default')
  })

  it('should handle mixing namespace imports and named imports from client components', async () => {
    const $ = await next.render$('/client-import-namespace')

    // mixing namespace imports and named imports
    expect($('#a').text()).toContain('client-mod:export-a')
    expect($('#b').text()).toContain('client-mod:export-b')
    expect($('#c').text()).toContain('client-mod:export-c')
    expect($('#named-c').text()).toContain('client-mod:export-c')

    // only named exports
    expect($('#a2').text()).toContain('client-mod2:export-a')
    expect($('#b2').text()).toContain('client-mod2:export-b')
  })

  it('should only include imported relative components in browser bundle with direct imports', async () => {
    const $ = await next.render$('/relative-dep')
    const chunkContents = await Promise.all(
      $('script[src]')
        .toArray()
        .map(async (el) => {
          const href = $(el).attr('src')

          const file = await next.fetch(href).then((res) => res.text())

          return file
        })
    )

    expect(
      chunkContents.some((content) => content.includes('client-comp-imported'))
    ).toBe(true)
    expect(
      chunkContents.every((content) => content.includes('client-comp-unused'))
    ).toBe(false)
    expect(
      chunkContents.every((content) => content.includes('client-comp-default'))
    ).toBe(false)
  })
})