next.js/test/unit/next-babel-loader-prod.test.ts

/* eslint-env jest */
import os from 'os'
import path from 'path'
import { Span } from 'next/dist/trace'
import loader from 'next/dist/build/babel/loader'

const dir = path.resolve(os.tmpdir())

const babel = async (code: string, queryOpts = {} as any) => {
  const { isServer = false, resourcePath = `index.js` } = queryOpts

  let isAsync = false
  return new Promise<string>((resolve, reject) => {
    function callback(err, content) {
      if (err) {
        reject(err)
      } else {
        resolve(content.replace(/\n/g, ''))
      }
    }

    const options = {
      // loader opts
      cwd: dir,
      isServer,
      distDir: path.resolve(dir, '.next'),
      pagesDir:
        'pagesDir' in queryOpts
          ? queryOpts.pagesDir
          : path.resolve(dir, 'pages'),
      cache: false,
      hasReactRefresh: false,
    }

    const res = loader.bind({
      resourcePath,
      async() {
        isAsync = true
        return callback
      },
      callback,
      emitWarning() {},
      query: options,
      getOptions: function () {
        return options
      },
      currentTraceSpan: new Span({ name: 'test' }),
    })(code, null)

    if (!isAsync) {
      resolve(res)
    }
  })
}

describe('next-babel-loader', () => {
  describe('replace constants', () => {
    it('should replace typeof window expression nested', async () => {
      const code = await babel('function a(){console.log(typeof window)}')
      expect(code).toMatchInlineSnapshot(
        `"function a() {  console.log("object");}"`
      )
    })

    it('should replace typeof window expression top level (client)', async () => {
      const code = await babel('typeof window;')
      expect(code).toMatchInlineSnapshot(`""object";"`)
    })

    it('should replace typeof window expression top level (server)', async () => {
      const code = await babel('typeof window;', { isServer: true })
      expect(code).toMatchInlineSnapshot(`""undefined";"`)
    })

    it('should replace typeof window in === expression nested', async () => {
      const code = await babel(
        `function a(){console.log(typeof window === 'undefined')}`
      )
      expect(code).toMatchInlineSnapshot(
        `"function a() {  console.log(false);}"`
      )
    })

    it('should replace typeof window expression top level', async () => {
      const code = await babel(`typeof window === 'undefined';`)
      expect(code).toMatchInlineSnapshot(`"false;"`)
    })

    it('should replace typeof window in === expression top level', async () => {
      const code = await babel(`typeof window === 'object';`)
      expect(code).toMatchInlineSnapshot(`"true;"`)
    })

    it('should replace typeof window in !== expression top level', async () => {
      const code = await babel(`typeof window !== 'undefined';`)
      expect(code).toMatchInlineSnapshot(`"true;"`)
    })

    it('should replace typeof window expression !== object top level', async () => {
      const code = await babel(`typeof window !== 'object';`)
      expect(code).toMatchInlineSnapshot(`"false;"`)
    })

    it('should replace typeof window expression top level serverside', async () => {
      const code = await babel(`typeof window !== 'undefined';`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"false;"`)
    })

    it('should replace typeof window expression !== object top level serverside', async () => {
      const code = await babel(`typeof window !== 'object';`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"true;"`)
    })

    it('should replace process.browser (1)', async () => {
      const code = await babel(`process.browser`, {
        isServer: false,
      })
      expect(code).toMatchInlineSnapshot(`"true;"`)
    })

    it('should replace process.browser (2)', async () => {
      const code = await babel(`process.browser`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"false;"`)
    })

    it('should replace process.browser (3)', async () => {
      const code = await babel(`process.browser == false`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"true;"`)
    })

    it('should replace process.browser (4)', async () => {
      const code = await babel(`if (process.browser === false) {}`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"if (true) {}"`)
    })

    it('should replace process.browser (5)', async () => {
      const code = await babel(`if (process.browser) {}`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`"if (false) {}"`)
    })

    it('should replace NODE_ENV on client (prod)', async () => {
      const code = await babel(`process.env.NODE_ENV`, {
        isServer: false,
      })
      expect(code).toMatchInlineSnapshot(`""production";"`)
    })

    it('should replace NODE_ENV on server', async () => {
      const code = await babel(`process.env.NODE_ENV`, {
        isServer: true,
      })
      expect(code).toMatchInlineSnapshot(`""production";"`)
    })

    it('should replace NODE_ENV in === statement (prod)', async () => {
      const code = await babel(`if (process.env.NODE_ENV === 'production') {}`)
      expect(code).toMatchInlineSnapshot(`"if (true) {}"`)
    })

    it('should replace NODE_ENV in !== statement (prod)', async () => {
      const code = await babel(`if (process.env.NODE_ENV !== 'production') {}`)
      expect(code).toMatchInlineSnapshot(`"if (false) {}"`)
    })

    it('should handle no pagesDir', async () => {
      const code = await babel(
        `
        import dynamic from 'next/dynamic'
        
        const Comp = dynamic(() => import('comp'))
        
        export default function Page(props) {
          return <Comp />
        }
      `,
        {
          pagesDir: undefined,
        }
      )
      expect(
        code.replace(/modules: \[".*?"/, 'modules:["/path/to/page"')
      ).toMatchInlineSnapshot(
        `"var _jsxFileName = "index.js";import React from "react";var __jsx = React.createElement;import dynamic from 'next/dynamic';const Comp = dynamic(() => import('comp'), {  loadableGenerated: {    webpack: () => [require.resolveWeak('comp')]  }});export default function Page(props) {  return __jsx(Comp, {    __self: this,    __source: {      fileName: _jsxFileName,      lineNumber: 7,      columnNumber: 18    }  });}"`
      )
    })

    it('should not drop unused exports by default', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";` +
          // complex
          `import * as React from "react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";`
      )
      expect(code).toMatchInlineSnapshot(
        `"import "core-js";import { foo, bar } from "a";import baz from "b";import * as React from "react";import baz2, { yeet } from "c";import baz3, { cats } from "d";import { c, d } from "e";import { e as ee, f as ff } from "f";"`
      )
    })

    const pageFile = path.resolve(dir, 'pages', 'index.js')

    it('should not drop unused exports by default in a page', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";` +
          // complex
          `import*as React from"react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";`,
        { resourcePath: pageFile }
      )
      expect(code).toMatchInlineSnapshot(
        `"import "core-js";import { foo, bar } from "a";import baz from "b";import * as React from "react";import baz2, { yeet } from "c";import baz3, { cats } from "d";import { c, d } from "e";import { e as ee, f as ff } from "f";"`
      )
    })

    it('should drop unused exports in a modern-apis page', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";` +
          // complex
          `import*as React from"react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";` +
          `` +
          `export function getStaticProps() {foo;bar;baz;cats;baz2;ff; return { props: {} } }`,
        { resourcePath: pageFile }
      )
      expect(code).toMatchInlineSnapshot(
        `"import "core-js";import * as React from "react";import { yeet } from "c";import baz3 from "d";import { c, d } from "e";import { e as ee } from "f";"`
      )
    })

    it('should keep used exports in a modern-apis page (server)', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";import ooo from"ooo";` +
          // complex
          `import*as React from"react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";` +
          `` +
          `export function getStaticProps() {foo();baz2();ff();ooo(); return { props: {} }}` +
          `export default function () { return bar(); }`,
        { resourcePath: pageFile, isServer: true }
      )
      expect(code).toMatchInlineSnapshot(
        `"import "core-js";import { foo, bar } from "a";import baz from "b";import ooo from "ooo";import * as React from "react";import baz2, { yeet } from "c";import baz3, { cats } from "d";import { c, d } from "e";import { e as ee, f as ff } from "f";export function getStaticProps() {  foo();  baz2();  ff();  ooo();  return {    props: {}  };}export default function () {  return bar();}"`
      )
    })

    it('should keep used exports in a modern-apis page (client)', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";import ooo from"ooo";` +
          // complex
          `import*as React from"react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";` +
          `` +
          `export function getStaticProps() {foo();baz2();ff();ooo();cats; return { props: {} }}` +
          `export default function () { return cats + bar(); }`,
        { resourcePath: pageFile, isServer: false }
      )
      expect(code).toMatchInlineSnapshot(
        `"import "core-js";import { bar } from "a";import baz from "b";import * as React from "react";import { yeet } from "c";import baz3, { cats } from "d";import { c, d } from "e";import { e as ee } from "f";export var __N_SSG = true;export default function () {  return cats + bar();}"`
      )
    })

    it('should keep used exports and react in a modern-apis page with JSX (client)', async () => {
      const code = await babel(
        // effectful
        `import"core-js";` +
          // basic
          `import{foo,bar}from"a";import baz from"b";import ooo from"ooo";` +
          // complex
          `import*as React from"react";` +
          `import baz2,{yeet}from"c";` +
          `import baz3,{cats}from"d";` +
          `import{c,d}from"e";` +
          `import{e as ee,f as ff}from"f";` +
          `` +
          `export function getStaticProps() {foo();baz2();ff();ooo(); return { props: {} }}` +
          `export default function () { return <div>{cats + bar()}</div> }`,
        { resourcePath: pageFile, isServer: false }
      )
      expect(code).toContain(
        `var __jsx = React.createElement;import "core-js";import { bar } from "a";import baz from "b";import * as React from "react";import { yeet } from "c";import baz3, { cats } from "d";import { c, d } from "e";import { e as ee } from "f";export var __N_SSG = true;export default function () {  return __jsx("div", {    __self: this,    __source: {      fileName: _jsxFileName,      lineNumber: 1,      columnNumber: 326    }  }, cats + bar());}`
      )
    })
  })
})