refactor(cli): better consistency and easier unit testing (#4160)

packages/cli/bin/nuxt.js

@@ -1,44 +1,3 @@
 #!/usr/bin/env node
 
-const consola = require('consola')
+require('../dist/cli.js').run()
-const cli = require('../dist/cli.js')
-
-// Global error handler
-process.on('unhandledRejection', (err) => {
-  consola.error(err)
-})
-
-// Exit process on fatal errors
-consola.add({
-  log(logObj) {
-    if (logObj.type === 'fatal') {
-      process.stderr.write('Nuxt Fatal Error :(\n')
-      process.exit(1)
-    }
-  }
-})
-
-const defaultCommand = 'dev'
-const commands = new Set([
-  defaultCommand,
-  'build',
-  'start',
-  'generate'
-])
-
-let cmd = process.argv[2]
-
-if (commands.has(cmd)) {
-  process.argv.splice(2, 1)
-} else {
-  cmd = defaultCommand
-}
-
-// Apply default NODE_ENV if not provided
-if (!process.env.NODE_ENV) {
-  process.env.NODE_ENV = cmd === 'dev' ? 'development' : 'production'
-}
-
-cli[cmd]().then(m => m.default()).catch((error) => {
-  consola.fatal(error)
-})

packages/cli/package.json

@@ -14,7 +14,8 @@
   "dependencies": {
     "consola": "^1.4.4",
     "esm": "^3.0.84",
-    "minimist": "^1.2.0"
+    "minimist": "^1.2.0",
+    "wrap-ansi": "^4.0.0"
   },
   "publishConfig": {
     "access": "public"

packages/cli/src/command.js

@@ -0,0 +1,143 @@
+import parseArgs from 'minimist'
+import wrapAnsi from 'wrap-ansi'
+import { name, version } from '../package.json'
+import { loadNuxtConfig, indent, indentLines, foldLines } from './utils'
+import { options as Options, defaultOptions as DefaultOptions } from './options'
+import * as imports from './imports'
+
+const startSpaces = 6
+const optionSpaces = 2
+const maxCharsPerLine = 80
+
+export default class NuxtCommand {
+  constructor({ description, usage, options } = {}) {
+    this.description = description || ''
+    this.usage = usage || ''
+    this.options = Array.from(new Set((options || []).concat(DefaultOptions)))
+  }
+
+  _getMinimistOptions() {
+    const minimistOptions = {
+      alias: {},
+      boolean: [],
+      string: [],
+      default: {}
+    }
+
+    for (const name of this.options) {
+      const option = Options[name]
+
+      if (option.alias) {
+        minimistOptions.alias[option.alias] = name
+      }
+      if (option.type) {
+        minimistOptions[option.type].push(option.alias || name)
+      }
+      if (option.default) {
+        minimistOptions.default[option.alias || name] = option.default
+      }
+    }
+
+    return minimistOptions
+  }
+
+  getArgv(args) {
+    const minimistOptions = this._getMinimistOptions()
+    const argv = parseArgs(args || process.argv.slice(2), minimistOptions)
+
+    if (argv.version) {
+      this.showVersion()
+    } else if (argv.help) {
+      this.showHelp()
+    }
+
+    return argv
+  }
+
+  async getNuxtConfig(argv, extraOptions) {
+    const config = await loadNuxtConfig(argv)
+    const options = Object.assign(config, extraOptions || {})
+
+    for (const name of this.options) {
+      if (Options[name].handle) {
+        Options[name].handle(options, argv)
+      }
+    }
+
+    return options
+  }
+
+  importCore() {
+    return imports.core()
+  }
+
+  importBuilder() {
+    return imports.builder()
+  }
+
+  importGenerator() {
+    return imports.generator()
+  }
+
+  async getNuxt(options) {
+    const { Nuxt } = await this.importCore()
+    return new Nuxt(options)
+  }
+
+  async getBuilder(nuxt) {
+    const { Builder } = await this.importBuilder()
+    return new Builder(nuxt)
+  }
+
+  async getGenerator(nuxt) {
+    const { Generator } = await this.importGenerator()
+    const { Builder } = await this.importBuilder()
+    return new Generator(nuxt, new Builder(nuxt))
+  }
+
+  _getHelp() {
+    const options = []
+
+    let maxOptionLength = 0
+    // For consistency Options determines order
+    for (const name in Options) {
+      const option = Options[name]
+      if (this.options.includes(name)) {
+        let optionHelp = '--'
+        optionHelp += option.type === 'boolean' && option.default ? 'no-' : ''
+        optionHelp += name
+        if (option.alias) {
+          optionHelp += `, -${option.alias}`
+        }
+
+        maxOptionLength = Math.max(maxOptionLength, optionHelp.length)
+        options.push([ optionHelp, option.description ])
+      }
+    }
+
+    const optionStr = options.map(([option, description]) => {
+      const line = option +
+        indent(maxOptionLength + optionSpaces - option.length) +
+        wrapAnsi(description, maxCharsPerLine - startSpaces - maxOptionLength - optionSpaces)
+      return indentLines(line, startSpaces + maxOptionLength + optionSpaces, startSpaces)
+    }).join('\n')
+
+    const description = foldLines(this.description, maxCharsPerLine, startSpaces)
+
+    return `
+    Description\n${description}
+    Usage
+      $ nuxt ${this.usage}
+    Options\n${optionStr}\n\n`
+  }
+
+  showVersion() {
+    process.stdout.write(`${name} v${version}\n`)
+    process.exit(0)
+  }
+
+  showHelp() {
+    process.stdout.write(this._getHelp())
+    process.exit(0)
+  }
+}

packages/cli/src/commands/build.js

@@ -1,91 +1,46 @@
-import parseArgs from 'minimist'
 import consola from 'consola'
-
+import NuxtCommand from '../command'
-import { loadNuxtConfig } from '../common/utils'
 
 export default async function build() {
-  const { Nuxt } = await import('@nuxt/core')
+  const nuxtCmd = new NuxtCommand({
-  const { Builder } = await import('@nuxt/builder')
+    description: 'Compiles the application for production deployment',
-  const { Generator } = await import('@nuxt/generator')
+    usage: 'build <dir>',
-
+    options: [ 'analyze', 'quiet' ]
-  const argv = parseArgs(process.argv.slice(2), {
-    alias: {
-      h: 'help',
-      c: 'config-file',
-      a: 'analyze',
-      s: 'spa',
-      u: 'universal',
-      q: 'quiet'
-    },
-    boolean: ['h', 'a', 's', 'u', 'q'],
-    string: ['c'],
-    default: {
-      c: 'nuxt.config.js'
-    }
   })
 
-  if (argv.help) {
+  const argv = nuxtCmd.getArgv()
-    process.stderr.write(`
-    Description
-      Compiles the application for production deployment
-    Usage
-      $ nuxt build <dir>
-    Options
-      --analyze, -a        Launch webpack-bundle-analyzer to optimize your bundles.
-      --spa, -s            Launch in SPA mode
-      --universal, -u      Launch in Universal mode (default)
-      --no-generate        Don't generate static version for SPA mode (useful for nuxt start)
-      --config-file, -c    Path to Nuxt.js config file (default: nuxt.config.js)
-      --quiet, -q          Disable output except for errors
-      --help, -h           Displays this message
-  `)
-    process.exit(0)
-  }
 
-  const options = await loadNuxtConfig(argv)
+  // Create production build when calling `nuxt build` (dev: false)
-
+  const nuxt = await nuxtCmd.getNuxt(
-  // Create production build when calling `nuxt build`
+    await nuxtCmd.getNuxtConfig(argv, { dev: false })
-  options.dev = false
+  )
-
-  // Analyze option
-  options.build = options.build || {}
-  if (argv.analyze && typeof options.build.analyze !== 'object') {
-    options.build.analyze = true
-  }
-
-  // Silence output when using --quiet
-  if (argv.quiet) {
-    options.build.quiet = !!argv.quiet
-  }
-
-  const nuxt = new Nuxt(options)
-  const builder = new Builder(nuxt)
 
   // Setup hooks
   nuxt.hook('error', err => consola.fatal(err))
 
-  // Close function
+  let builderOrGenerator
-  const close = () => {
+  if (nuxt.options.mode !== 'spa' || argv.generate === false) {
-    // In analyze mode wait for plugin
-    // emitting assets and opening browser
-    if (options.build.analyze === true || typeof options.build.analyze === 'object') {
-      return
-    }
-
-    process.exit(0)
-  }
-
-  if (options.mode !== 'spa' || argv.generate === false) {
     // Build only
-    return builder
+    builderOrGenerator = (await nuxtCmd.getBuilder(nuxt)).build()
-      .build()
-      .then(close)
-      .catch(err => consola.fatal(err))
   } else {
     // Build + Generate for static deployment
-    return new Generator(nuxt, builder)
+    builderOrGenerator = (await nuxtCmd.getGenerator(nuxt)).generate({
-      .generate({ build: true })
+      build: true
-      .then(close)
+    })
-      .catch(err => consola.fatal(err))
   }
+
+  return builderOrGenerator
+    .then(() => {
+      // In analyze mode wait for plugin
+      // emitting assets and opening browser
+      if (
+        nuxt.options.build.analyze === true ||
+        typeof nuxt.options.build.analyze === 'object'
+      ) {
+        return
+      }
+
+      process.exit(0)
+    })
+    .catch(err => consola.fatal(err))
 }

packages/cli/src/commands/dev.js

@@ -1,71 +1,29 @@
-import parseArgs from 'minimist'
 import consola from 'consola'
-import { loadNuxtConfig, runAsyncScript } from '../common/utils'
+import NuxtCommand from '../command'
 
 export default async function dev() {
-  const { Nuxt } = await import('@nuxt/core')
+  const nuxtCmd = new NuxtCommand({
-  const { Builder } = await import('@nuxt/builder')
+    description: 'Start the application in development mode (e.g. hot-code reloading, error reporting)',
-
+    usage: 'dev <dir> -p <port number> -H <hostname>',
-  const argv = parseArgs(process.argv.slice(2), {
+    options: [ 'hostname', 'port' ]
-    alias: {
-      h: 'help',
-      H: 'hostname',
-      p: 'port',
-      c: 'config-file',
-      s: 'spa',
-      u: 'universal',
-      v: 'version'
-    },
-    boolean: ['h', 's', 'u', 'v'],
-    string: ['H', 'c'],
-    default: {
-      c: 'nuxt.config.js'
-    }
   })
 
-  if (argv.version) {
+  const argv = nuxtCmd.getArgv()
-    process.stderr.write('TODO' + '\n')
-    process.exit(0)
-  }
-
-  if (argv.hostname === '') {
-    consola.fatal('Provided hostname argument has no value')
-  }
-
-  if (argv.help) {
-    process.stderr.write(`
-    Description
-      Starts the application in development mode (hot-code reloading, error
-      reporting, etc)
-    Usage
-      $ nuxt dev <dir> -p <port number> -H <hostname>
-    Options
-      --port, -p          A port number on which to start the application
-      --hostname, -H      Hostname on which to start the application
-      --spa               Launch in SPA mode
-      --universal         Launch in Universal mode (default)
-      --config-file, -c   Path to Nuxt.js config file (default: nuxt.config.js)
-      --help, -h          Displays this message
-  `)
-    process.exit(0)
-  }
-
-  const config = async () => {
-    // Force development mode for add hot reloading and watching changes
-    return Object.assign(await loadNuxtConfig(argv), { dev: true })
-  }
 
   const errorHandler = (err, instance) => {
     instance && instance.builder.watchServer()
     consola.error(err)
   }
 
+  const { Nuxt } = await nuxtCmd.importCore()
+  const { Builder } = await nuxtCmd.importBuilder()
+
   // Start dev
   async function startDev(oldInstance) {
     let nuxt, builder
 
     try {
-      nuxt = new Nuxt(await config())
+      nuxt = new Nuxt(await nuxtCmd.getNuxtConfig(argv, { dev: true }))
       builder = new Builder(nuxt)
       nuxt.hook('watch:fileChanged', async (builder, fname) => {
         consola.debug(`[${fname}] changed, Rebuilding the app...`)
@@ -81,10 +39,10 @@ export default async function dev() {
         .then(() => oldInstance && oldInstance.builder.unwatch())
         // Start build
         .then(() => builder.build())
-        // Close old nuxt no mater if build successfully
+        // Close old nuxt no matter if build successfully
         .catch((err) => {
           oldInstance && oldInstance.nuxt.close()
-          // Jump to eventHandler
+          // Jump to errorHandler
           throw err
         })
         .then(() => oldInstance && oldInstance.nuxt.close())
@@ -98,5 +56,5 @@ export default async function dev() {
     )
   }
 
-  await runAsyncScript(startDev)
+  await startDev()
 }

packages/cli/src/commands/generate.js

@@ -1,61 +1,25 @@
-import parseArgs from 'minimist'
 import consola from 'consola'
-
+import NuxtCommand from '../command'
-import { loadNuxtConfig } from '../common/utils'
 
 export default async function generate() {
-  const { Nuxt } = await import('@nuxt/core')
+  const nuxtCmd = new NuxtCommand({
-  const { Builder } = await import('@nuxt/builder')
+    description: 'Generate a static web application (server-rendered)',
-  const { Generator } = await import('@nuxt/generator')
+    usage: 'generate <dir>',
-
+    options: [ 'build' ]
-  const argv = parseArgs(process.argv.slice(2), {
-    alias: {
-      h: 'help',
-      c: 'config-file',
-      s: 'spa',
-      u: 'universal'
-    },
-    boolean: ['h', 's', 'u', 'build'],
-    string: ['c'],
-    default: {
-      c: 'nuxt.config.js',
-      build: true
-    }
   })
 
-  if (argv.help) {
+  const argv = nuxtCmd.getArgv()
-    process.stderr.write(`
-    Description
-      Generate a static web application (server-rendered)
-    Usage
-      $ nuxt generate <dir>
-    Options
-      --spa              Launch in SPA mode
-      --universal        Launch in Universal mode (default)
-      --config-file, -c  Path to Nuxt.js config file (default: nuxt.config.js)
-      --help, -h         Displays this message
-      --no-build         Just run generate for faster builds when just dynamic routes changed. Nuxt build is needed before this command.
-  `)
-    process.exit(0)
-  }
 
-  const options = await loadNuxtConfig(argv)
+  const generator = await nuxtCmd.getGenerator(
+    await nuxtCmd.getNuxt(
+      await nuxtCmd.getNuxtConfig(argv, { dev: false })
+    )
+  )
 
-  options.dev = false // Force production mode (no webpack middleware called)
+  return generator.generate({
-
-  const nuxt = new Nuxt(options)
-  const builder = new Builder(nuxt)
-  const generator = new Generator(nuxt, builder)
-
-  const generateOptions = {
     init: true,
     build: argv.build
-  }
+  }).then(() => {
-
+    process.exit(0)
-  return generator
+  }).catch(err => consola.fatal(err))
-    .generate(generateOptions)
-    .then(() => {
-      process.exit(0)
-    })
-    .catch(err => consola.fatal(err))
 }

packages/cli/src/commands/index.js

@@ -0,0 +1,4 @@
+export const start = () => import('./start')
+export const dev = () => import('./dev')
+export const build = () => import('./build')
+export const generate = () => import('./generate')

packages/cli/src/commands/start.js

@@ -1,59 +1,21 @@
 import fs from 'fs'
 import path from 'path'
-import parseArgs from 'minimist'
 import consola from 'consola'
-
+import NuxtCommand from '../command'
-import { loadNuxtConfig } from '../common/utils'
 
 export default async function start() {
-  const { Nuxt } = await import('@nuxt/core')
+  const nuxtCmd = new NuxtCommand({
-
+    description: 'Start the application in production mode (the application should be compiled with `nuxt build` first)',
-  const argv = parseArgs(process.argv.slice(2), {
+    usage: 'start <dir> -p <port number> -H <hostname>',
-    alias: {
+    options: [ 'hostname', 'port', 'unix-socket' ]
-      h: 'help',
-      H: 'hostname',
-      p: 'port',
-      n: 'unix-socket',
-      c: 'config-file',
-      s: 'spa',
-      u: 'universal'
-    },
-    boolean: ['h', 's', 'u'],
-    string: ['H', 'c', 'n'],
-    default: {
-      c: 'nuxt.config.js'
-    }
   })
 
-  if (argv.hostname === '') {
+  const argv = nuxtCmd.getArgv()
-    consola.fatal('Provided hostname argument has no value')
-  }
 
-  if (argv.help) {
+  // Create production build when calling `nuxt build`
-    process.stderr.write(`
+  const nuxt = await nuxtCmd.getNuxt(
-    Description
+    await nuxtCmd.getNuxtConfig(argv, { dev: false })
-      Starts the application in production mode.
+  )
-      The application should be compiled with \`nuxt build\` first.
-    Usage
-      $ nuxt start <dir> -p <port number> -H <hostname>
-    Options
-      --port, -p            A port number on which to start the application
-      --hostname, -H        Hostname on which to start the application
-      --unix-socket, -n     Path to a UNIX socket
-      --spa                 Launch in SPA mode
-      --universal           Launch in Universal mode (default)
-      --config-file, -c     Path to Nuxt.js config file (default: nuxt.config.js)
-      --help, -h            Displays this message
-  `)
-    process.exit(0)
-  }
-
-  const options = await loadNuxtConfig(argv)
-
-  // Force production mode (no webpack middleware called)
-  options.dev = false
-
-  const nuxt = new Nuxt(options)
 
   // Setup hooks
   nuxt.hook('error', err => consola.fatal(err))

packages/cli/src/imports.js

@@ -0,0 +1,3 @@
+export const builder = () => import('@nuxt/builder')
+export const generator = () => import('@nuxt/generator')
+export const core = () => import('@nuxt/core')

packages/cli/src/index.js

@@ -1,5 +1,10 @@
-export const start = () => import('./commands/start')
+import * as _commands from './commands'
-export const dev = () => import('./commands/dev')
+import * as _imports from './imports'
 
-export const build = () => import('./commands/build')
+export const commands = _commands
-export const generate = () => import('./commands/generate')
+export const imports = _imports
+
+export { default as setup } from './setup'
+export { default as run } from './run'
+
+export { loadNuxtConfig } from './utils'

packages/cli/src/options.js

@@ -0,0 +1,101 @@
+import consola from 'consola'
+
+export const defaultOptions = [
+  'spa',
+  'universal',
+  'config-file',
+  'version',
+  'help'
+]
+
+export const options = {
+  port: {
+    alias: 'p',
+    type: 'string',
+    description: 'Port number on which to start the application',
+    handle(options, argv) {
+      if (argv.port) {
+        options.server.port = +argv.port
+      }
+    }
+  },
+  hostname: {
+    alias: 'H',
+    type: 'string',
+    description: 'Hostname on which to start the application',
+    handle(options, argv) {
+      if (argv.hostname === '') {
+        consola.fatal('Provided hostname argument has no value')
+      }
+    }
+  },
+  'unix-socket': {
+    alias: 'n',
+    type: 'string',
+    description: 'Path to a UNIX socket'
+  },
+  analyze: {
+    alias: 'a',
+    type: 'boolean',
+    description: 'Launch webpack-bundle-analyzer to optimize your bundles',
+    handle(options, argv) {
+      // Analyze option
+      options.build = options.build || {}
+      if (argv.analyze && typeof options.build.analyze !== 'object') {
+        options.build.analyze = true
+      }
+    }
+  },
+  build: {
+    type: 'boolean',
+    default: true,
+    description: 'Only generate pages for dynamic routes. Nuxt has to be built once before using this option'
+  },
+  generate: {
+    type: 'boolean',
+    default: true,
+    description: 'Don\'t generate static version for SPA mode (useful for nuxt start)'
+  },
+  spa: {
+    alias: 's',
+    type: 'boolean',
+    description: 'Launch in SPA mode'
+  },
+  universal: {
+    alias: 'u',
+    type: 'boolean',
+    description: 'Launch in Universal mode (default)'
+  },
+  'config-file': {
+    alias: 'c',
+    type: 'string',
+    default: 'nuxt.config.js',
+    description: 'Path to Nuxt.js config file (default: nuxt.config.js)'
+  },
+  quiet: {
+    alias: 'q',
+    type: 'boolean',
+    description: 'Disable output except for errors',
+    handle(options, argv) {
+      // Silence output when using --quiet
+      options.build = options.build || {}
+      if (argv.quiet) {
+        options.build.quiet = !!argv.quiet
+      }
+    }
+  },
+  verbose: {
+    alias: 'v',
+    type: 'boolean',
+    description: 'Show debug information'
+  },
+  version: {
+    type: 'boolean',
+    description: 'Display the Nuxt version'
+  },
+  help: {
+    alias: 'h',
+    type: 'boolean',
+    description: 'Display this message'
+  }
+}

packages/cli/src/run.js

@@ -0,0 +1,33 @@
+import consola from 'consola'
+import * as commands from './commands'
+import setup from './setup'
+
+export default function run() {
+  const defaultCommand = 'dev'
+
+  const cmds = new Set([
+    defaultCommand,
+    'build',
+    'start',
+    'generate'
+  ])
+
+  let cmd = process.argv[2]
+
+  if (cmds.has(cmd)) {
+    process.argv.splice(2, 1)
+  } else {
+    cmd = defaultCommand
+  }
+
+  // Setup runtime
+  setup({
+    dev: cmd === 'dev'
+  })
+
+  return commands[cmd]() // eslint-disable-line import/namespace
+    .then(m => m.default())
+    .catch((error) => {
+      consola.fatal(error)
+    })
+}

packages/cli/src/setup.js

@@ -0,0 +1,32 @@
+import consola from 'consola'
+
+let _setup = false
+
+export default function setup({ dev }) {
+  // Apply default NODE_ENV if not provided
+  if (!process.env.NODE_ENV) {
+    process.env.NODE_ENV = dev ? 'development' : 'production'
+  }
+
+  if (_setup) {
+    return
+  }
+  _setup = true
+
+  // Global error handler
+  /* istanbul ignore next */
+  process.on('unhandledRejection', (err) => {
+    consola.error(err)
+  })
+
+  // Exit process on fatal errors
+  /* istanbul ignore next */
+  consola.add({
+    log(logObj) {
+      if (logObj.type === 'fatal') {
+        process.stderr.write('Nuxt Fatal Error :(\n')
+        process.exit(1)
+      }
+    }
+  })
+}

packages/cli/src/utils.js

@@ -2,6 +2,7 @@ import path from 'path'
 import { existsSync } from 'fs'
 import consola from 'consola'
 import esm from 'esm'
+import wrapAnsi from 'wrap-ansi'
 
 const _require = esm(module, {
   cache: false,
@@ -33,15 +34,6 @@ const getLatestHost = (argv) => {
   return { port, host, socket }
 }
 
-export async function runAsyncScript(fn) {
-  try {
-    await fn()
-  } catch (err) {
-    consola.error(err)
-    consola.fatal(`Failed to run async Nuxt script!`)
-  }
-}
-
 export async function loadNuxtConfig(argv) {
   const rootDir = getRootDir(argv)
   const nuxtConfigFile = getNuxtConfigFile(argv)
@@ -50,16 +42,17 @@ export async function loadNuxtConfig(argv) {
 
   if (existsSync(nuxtConfigFile)) {
     delete require.cache[nuxtConfigFile]
-    options = _require(nuxtConfigFile)
+    options = _require(nuxtConfigFile) || {}
-    if (!options) {
-      options = {}
-    }
     if (options.default) {
       options = options.default
     }
+
     if (typeof options === 'function') {
       try {
         options = await options()
+        if (options.default) {
+          options = options.default
+        }
       } catch (error) {
         consola.error(error)
         consola.fatal('Error while fetching async configuration')
@@ -68,7 +61,6 @@ export async function loadNuxtConfig(argv) {
   } else if (argv['config-file'] !== 'nuxt.config.js') {
     consola.fatal('Could not load config file: ' + argv['config-file'])
   }
-
   if (typeof options.rootDir !== 'string') {
     options.rootDir = rootDir
   }
@@ -81,9 +73,33 @@ export async function loadNuxtConfig(argv) {
   if (!options.server) {
     options.server = {}
   }
+
   const { port, host, socket } = getLatestHost(argv)
   options.server.port = port || options.server.port || 3000
   options.server.host = host || options.server.host || 'localhost'
   options.server.socket = socket || options.server.socket
+
   return options
 }
+
+export function indent(count, chr = ' ') {
+  return chr.repeat(count)
+}
+
+export function indentLines(string, spaces, firstLineSpaces) {
+  const lines = Array.isArray(string) ? string : string.split('\n')
+  let s = ''
+  if (lines.length) {
+    const i0 = indent(firstLineSpaces === undefined ? spaces : firstLineSpaces)
+    s = i0 + lines.shift()
+  }
+  if (lines.length) {
+    const i = indent(spaces)
+    s += '\n' + lines.map(l => i + l.trim()).join('\n')
+  }
+  return s
+}
+
+export function foldLines(string, maxCharsPerLine, spaces, firstLineSpaces) {
+  return indentLines(wrapAnsi(string, maxCharsPerLine), spaces, firstLineSpaces)
+}

packages/cli/test/fixtures/nuxt.async-config.js

@@ -0,0 +1,9 @@
+import { resolve } from 'path'
+
+export default () => {
+  // delete cache is needed because otherwise Jest will return the same
+  // object reference as the previous test and then mode will not be
+  // set correctly. jest.resetModules doesnt work for some reason
+  delete require.cache[resolve(__dirname, 'nuxt.config.js')]
+  return import('./nuxt.config.js')
+}

packages/cli/test/fixtures/nuxt.async-error.js

@@ -0,0 +1 @@
+export default () => Promise.reject(new Error('Async Config Error'))

packages/cli/test/fixtures/nuxt.config.js

@@ -0,0 +1,10 @@
+export default {
+  testOption: true,
+  rootDir: '/some/path',
+  mode: 'supercharged',
+  server: {
+    host: 'nuxt-host',
+    port: 3001,
+    socket: '/var/run/nuxt.sock'
+  }
+}

packages/cli/test/unit/build.test.js

@@ -0,0 +1,62 @@
+import { consola, mockGetNuxt, mockGetBuilder, mockGetGenerator } from '../utils'
+
+describe('build', () => {
+  let build
+
+  beforeAll(async () => {
+    build = await import('../../src/commands/build')
+    build = build.default
+
+    jest.spyOn(process, 'exit').mockImplementation(code => code)
+  })
+
+  afterAll(() => {
+    process.exit.mockRestore()
+  })
+
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('is function', () => {
+    expect(typeof build).toBe('function')
+  })
+
+  test('builds on universal mode', async () => {
+    mockGetNuxt({
+      mode: 'universal',
+      build: {
+        analyze: true
+      }
+    })
+    const builder = mockGetBuilder(Promise.resolve())
+
+    await build()
+
+    expect(builder).toHaveBeenCalled()
+  })
+
+  test('generates on spa mode', async () => {
+    mockGetNuxt({
+      mode: 'spa',
+      build: {
+        analyze: false
+      }
+    })
+    const generate = mockGetGenerator(Promise.resolve())
+
+    await build()
+
+    expect(generate).toHaveBeenCalled()
+    expect(process.exit).toHaveBeenCalled()
+  })
+
+  test('catches error', async () => {
+    mockGetNuxt({ mode: 'universal' })
+    mockGetBuilder(Promise.reject(new Error('Builder Error')))
+
+    await build()
+
+    expect(consola.fatal).toHaveBeenCalledWith(new Error('Builder Error'))
+  })
+})

packages/cli/test/unit/cli.test.js

@@ -0,0 +1,95 @@
+import { readdir } from 'fs'
+import { resolve } from 'path'
+import { promisify } from 'util'
+import { consola } from '../utils'
+import { run } from '../../src'
+import * as commands from '../../src/commands'
+
+const readDir = promisify(readdir)
+
+consola.add = jest.fn()
+
+const mockCommand = (cmd, p) => {
+  commands[cmd] = jest.fn().mockImplementationOnce(() => { // eslint-disable-line import/namespace
+    return Promise.resolve({
+      default: () => {
+        return p
+      }
+    })
+  })
+}
+
+describe('cli', () => {
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('exports for all commands defined', async () => {
+    const cmds = await readDir(resolve(__dirname, '..', '..', 'src', 'commands'))
+
+    for (let cmd of cmds) {
+      if (cmd === 'index.js') {
+        continue
+      }
+      cmd = cmd.substring(0, cmd.length - 3)
+
+      expect(commands[cmd]).toBeDefined() // eslint-disable-line import/namespace
+      expect(typeof commands[cmd]).toBe('function') // eslint-disable-line import/namespace
+    }
+  })
+
+  test('calls expected method', async () => {
+    const argv = process.argv
+    process.argv = ['', '', 'dev']
+    mockCommand('dev', Promise.resolve())
+
+    await run()
+
+    expect(commands.dev).toHaveBeenCalled()
+    process.argv = argv
+  })
+
+  test('unknown calls default method', async () => {
+    const argv = process.argv
+    process.argv = ['', '', 'test']
+    mockCommand('dev', Promise.resolve())
+
+    await run()
+
+    expect(commands.dev).toHaveBeenCalled()
+    process.argv = argv
+  })
+
+  test('sets NODE_ENV=development for dev', async () => {
+    const nodeEnv = process.env.NODE_ENV
+    process.env.NODE_ENV = ''
+    mockCommand('dev', Promise.resolve())
+
+    await run()
+
+    expect(process.env.NODE_ENV).toBe('development')
+    process.env.NODE_ENV = nodeEnv
+  })
+
+  test('sets ODE_ENV=production for build', async () => {
+    const argv = process.argv
+    const nodeEnv = process.env.NODE_ENV
+    process.argv = ['', '', 'build']
+    process.env.NODE_ENV = ''
+    mockCommand('build', Promise.resolve())
+
+    await run()
+
+    expect(process.env.NODE_ENV).toBe('production')
+    process.argv = argv
+    process.env.NODE_ENV = nodeEnv
+  })
+
+  test('catches fatal error', async () => {
+    mockCommand('dev', Promise.reject(new Error('Command Error')))
+
+    await run()
+
+    expect(consola.fatal).toHaveBeenCalledWith(new Error('Command Error'))
+  })
+})

packages/cli/test/unit/command.test.js

@@ -0,0 +1,169 @@
+import { consola } from '../utils'
+import Command from '../../src/command'
+import { options as Options } from '../../src/options'
+
+jest.mock('@nuxt/core')
+jest.mock('@nuxt/builder')
+jest.mock('@nuxt/generator')
+
+describe('cli/command', () => {
+  beforeEach(() => {
+    jest.restoreAllMocks()
+  })
+
+  test('adds default options', () => {
+    const cmd = new Command()
+
+    expect(cmd.options.length).not.toBe(0)
+  })
+
+  test('builds minimist options', () => {
+    const cmd = new Command({
+      options: Object.keys(Options)
+    })
+
+    const minimistOptions = cmd._getMinimistOptions()
+
+    expect(minimistOptions.string.length).toBe(4)
+    expect(minimistOptions.boolean.length).toBe(9)
+    expect(minimistOptions.alias.c).toBe('config-file')
+    expect(minimistOptions.default.c).toBe(Options['config-file'].default)
+  })
+
+  test('parses args', () => {
+    const cmd = new Command({
+      options: Object.keys(Options)
+    })
+
+    let args = ['-c', 'test-file', '-s', '-p', '3001']
+    let argv = cmd.getArgv(args)
+
+    expect(argv['config-file']).toBe(args[1])
+    expect(argv.spa).toBe(true)
+    expect(argv.universal).toBe(false)
+    expect(argv.build).toBe(true)
+    expect(argv.port).toBe('3001')
+
+    args = ['--no-build']
+    argv = cmd.getArgv(args)
+
+    expect(argv.build).toBe(false)
+  })
+
+  test('prints version automatically', () => {
+    const cmd = new Command()
+    cmd.showVersion = jest.fn()
+
+    const args = ['--version']
+    cmd.getArgv(args)
+
+    expect(cmd.showVersion).toHaveBeenCalledTimes(1)
+  })
+
+  test('prints help automatically', () => {
+    const cmd = new Command()
+    cmd.showHelp = jest.fn()
+
+    const args = ['-h']
+    cmd.getArgv(args)
+
+    expect(cmd.showHelp).toHaveBeenCalledTimes(1)
+  })
+
+  test('returns nuxt config', async () => {
+    const cmd = new Command({
+      options: Object.keys(Options)
+    })
+
+    const args = ['-c', 'test-file', '-a', '-p', '3001', '-q', '-H']
+    const argv = cmd.getArgv(args)
+    argv._ = ['.']
+
+    const options = await cmd.getNuxtConfig(argv, { testOption: true })
+
+    expect(options.testOption).toBe(true)
+    expect(options.server.port).toBe(3001)
+    expect(options.build.quiet).toBe(true)
+    expect(options.build.analyze).toBe(true)
+    expect(consola.fatal).toHaveBeenCalledWith('Provided hostname argument has no value') // hostname check
+  })
+
+  test('returns Nuxt instance', async () => {
+    const cmd = new Command()
+    const nuxt = await cmd.getNuxt()
+
+    expect(nuxt.constructor.name).toBe('Nuxt')
+    expect(typeof nuxt.ready).toBe('function')
+  })
+
+  test('returns Builder instance', async () => {
+    const cmd = new Command()
+    const builder = await cmd.getBuilder()
+
+    expect(builder.constructor.name).toBe('Builder')
+    expect(typeof builder.build).toBe('function')
+  })
+
+  test('returns Generator instance', async () => {
+    const cmd = new Command()
+    const generator = await cmd.getGenerator()
+
+    expect(generator.constructor.name).toBe('Generator')
+    expect(typeof generator.generate).toBe('function')
+  })
+
+  test('builds help text', () => {
+    const cmd = new Command({
+      description: 'a very long description that is longer than 80 chars and ' +
+        'should wrap to the next line while keeping indentation',
+      usage: 'this is how you do it',
+      options: ['build']
+    })
+
+    const expectedText = `
+    Description
+      a very long description that is longer than 80 chars and should wrap to the next
+      line while keeping indentation
+    Usage
+      $ nuxt this is how you do it
+    Options
+      --no-build         Only generate pages for dynamic routes. Nuxt has to be
+                         built once before using this option
+      --spa, -s          Launch in SPA mode
+      --universal, -u    Launch in Universal mode (default)
+      --config-file, -c  Path to Nuxt.js config file (default: nuxt.config.js)
+      --version          Display the Nuxt version
+      --help, -h         Display this message
+
+`
+    expect(cmd._getHelp()).toBe(expectedText)
+  })
+
+  test('show version prints to stdout and exits', () => {
+    jest.spyOn(process.stdout, 'write').mockImplementation(() => {})
+    jest.spyOn(process, 'exit').mockImplementationOnce(code => code)
+
+    const cmd = new Command()
+    cmd.showVersion()
+
+    expect(process.stdout.write).toHaveBeenCalled()
+    expect(process.exit).toHaveBeenCalled()
+
+    process.stdout.write.mockRestore()
+    process.exit.mockRestore()
+  })
+
+  test('show help prints to stdout and exits', () => {
+    jest.spyOn(process.stdout, 'write').mockImplementation(() => {})
+    jest.spyOn(process, 'exit').mockImplementationOnce(code => code)
+
+    const cmd = new Command()
+    cmd.showHelp()
+
+    expect(process.stdout.write).toHaveBeenCalled()
+    expect(process.exit).toHaveBeenCalled()
+
+    process.stdout.write.mockRestore()
+    process.exit.mockRestore()
+  })
+})

packages/cli/test/unit/dev.test.js

@@ -0,0 +1,114 @@
+import { consola } from '../utils'
+import { mockNuxt, mockBuilder, mockGetNuxtConfig } from '../utils/mocking'
+
+describe('dev', () => {
+  let dev
+
+  beforeAll(async () => {
+    dev = await import('../../src/commands/dev')
+    dev = dev.default
+  })
+
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('is function', () => {
+    expect(typeof dev).toBe('function')
+  })
+
+  test('reloads on fileChanged hook', async () => {
+    const Nuxt = mockNuxt()
+    const Builder = mockBuilder()
+
+    await dev()
+
+    expect(consola.error).not.toHaveBeenCalled()
+
+    expect(Builder.prototype.build).toHaveBeenCalled()
+    expect(Nuxt.prototype.listen).toHaveBeenCalled()
+    expect(Nuxt.prototype.showReady).toHaveBeenCalled()
+    expect(Builder.prototype.watchServer).toHaveBeenCalled()
+
+    jest.resetAllMocks()
+
+    const builder = new Builder()
+    builder.nuxt = new Nuxt()
+    await Nuxt.fileChangedHook(builder)
+    expect(consola.debug).toHaveBeenCalled()
+
+    expect(Nuxt.prototype.clearHook).toHaveBeenCalled()
+    expect(Builder.prototype.unwatch).toHaveBeenCalled()
+    expect(Builder.prototype.build).toHaveBeenCalled()
+    expect(Nuxt.prototype.close).toHaveBeenCalled()
+    expect(Nuxt.prototype.listen).toHaveBeenCalled()
+    expect(Nuxt.prototype.showReady).not.toHaveBeenCalled()
+    expect(Builder.prototype.watchServer).toHaveBeenCalled()
+
+    expect(consola.error).not.toHaveBeenCalled()
+  })
+
+  test('catches build error', async () => {
+    const Nuxt = mockNuxt()
+    const Builder = mockBuilder()
+
+    await dev()
+    jest.resetAllMocks()
+
+    // Test error on second build so we cover oldInstance stuff
+    const builder = new Builder()
+    builder.nuxt = new Nuxt()
+    Builder.prototype.build = jest.fn().mockImplementationOnce(() => Promise.reject(new Error('Build Error')))
+    await Nuxt.fileChangedHook(builder)
+
+    expect(Nuxt.prototype.close).toHaveBeenCalled()
+    expect(consola.error).toHaveBeenCalledWith(new Error('Build Error'))
+  })
+
+  test('catches watchServer error', async () => {
+    const Nuxt = mockNuxt()
+    const Builder = mockBuilder()
+
+    await dev()
+    jest.resetAllMocks()
+
+    const builder = new Builder()
+    builder.nuxt = new Nuxt()
+    Builder.prototype.watchServer = jest.fn().mockImplementationOnce(() => Promise.reject(new Error('watchServer Error')))
+    await Nuxt.fileChangedHook(builder)
+
+    expect(consola.error).toHaveBeenCalledWith(new Error('watchServer Error'))
+    expect(Builder.prototype.watchServer).toHaveBeenCalledTimes(2)
+  })
+
+  test('catches error on hook error', async () => {
+    const Nuxt = mockNuxt()
+    const Builder = mockBuilder()
+
+    await dev()
+    jest.resetAllMocks()
+
+    mockGetNuxtConfig().mockImplementationOnce(() => {
+      throw new Error('Config Error')
+    })
+    const builder = new Builder()
+    builder.nuxt = new Nuxt()
+    await Nuxt.fileChangedHook(builder)
+
+    expect(consola.error).toHaveBeenCalledWith(new Error('Config Error'))
+    expect(Builder.prototype.watchServer).toHaveBeenCalledTimes(1)
+  })
+
+  test('catches error on startDev', async () => {
+    mockNuxt({
+      listen: jest.fn().mockImplementation(() => {
+        throw new Error('Listen Error')
+      })
+    })
+    mockBuilder()
+
+    await dev()
+
+    expect(consola.error).toHaveBeenCalledWith(new Error('Listen Error'))
+  })
+})

packages/cli/test/unit/generate.test.js

@@ -0,0 +1,64 @@
+import { consola, mockGetNuxt, mockGetGenerator } from '../utils'
+import Command from '../../src/command'
+
+describe('generate', () => {
+  let generate
+
+  beforeAll(async () => {
+    generate = await import('../../src/commands/generate')
+    generate = generate.default
+
+    jest.spyOn(process, 'exit').mockImplementation(code => code)
+  })
+
+  afterAll(() => {
+    process.exit.mockRestore()
+  })
+
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('is function', () => {
+    expect(typeof generate).toBe('function')
+  })
+
+  test('builds by default', async () => {
+    mockGetNuxt()
+    const generator = mockGetGenerator(Promise.resolve())
+
+    await generate()
+
+    expect(generator).toHaveBeenCalled()
+    expect(generator.mock.calls[0][0].build).toBe(true)
+  })
+
+  test('doesnt build with no-build', async () => {
+    mockGetNuxt()
+    const getArgv = Command.prototype.getArgv
+    Command.prototype.getArgv = jest.fn().mockImplementationOnce(() => {
+      return {
+        '_': ['.'],
+        rootDir: '.',
+        'config-file': 'nuxt.config.js',
+        build: false
+      }
+    })
+    const generator = mockGetGenerator(Promise.resolve())
+
+    await generate()
+
+    expect(generator).toHaveBeenCalled()
+    expect(generator.mock.calls[0][0].build).toBe(false)
+    Command.prototype.getArgv = getArgv
+  })
+
+  test('catches error', async () => {
+    mockGetNuxt()
+    mockGetGenerator(Promise.reject(new Error('Generator Error')))
+
+    await generate()
+
+    expect(consola.fatal).toHaveBeenCalledWith(new Error('Generator Error'))
+  })
+})

packages/cli/test/unit/start.test.js

@@ -0,0 +1,69 @@
+import fs from 'fs'
+import { consola, mockGetNuxtStart, mockGetNuxtConfig } from '../utils'
+
+describe('start', () => {
+  let start
+
+  beforeAll(async () => {
+    start = await import('../../src/commands/start')
+    start = start.default
+  })
+
+  afterEach(() => {
+    if (fs.existsSync.mockRestore) {
+      fs.existsSync.mockRestore()
+    }
+
+    jest.resetAllMocks()
+  })
+
+  test('is function', () => {
+    expect(typeof start).toBe('function')
+  })
+
+  test('starts listening and calls showReady', async () => {
+    const { listen, showReady } = mockGetNuxtStart()
+    await start()
+
+    expect(listen).toHaveBeenCalled()
+    expect(showReady).toHaveBeenCalled()
+  })
+
+  test('no error if dist dir exists', async () => {
+    mockGetNuxtStart()
+    mockGetNuxtConfig()
+    jest.spyOn(fs, 'existsSync').mockImplementationOnce(() => true)
+
+    await start()
+
+    expect(consola.fatal).not.toHaveBeenCalled()
+  })
+
+  test('fatal error if dist dir doesnt exist', async () => {
+    mockGetNuxtStart()
+    jest.spyOn(fs, 'existsSync').mockImplementationOnce(() => false)
+
+    await start()
+
+    expect(consola.fatal).toHaveBeenCalledWith('No build files found, please run `nuxt build` before launching `nuxt start`')
+  })
+
+  test('no error on ssr and server bundle exists', async () => {
+    mockGetNuxtStart(true)
+    mockGetNuxtConfig()
+    jest.spyOn(fs, 'existsSync').mockImplementation(() => true)
+
+    await start()
+
+    expect(consola.fatal).not.toHaveBeenCalled()
+  })
+
+  test('fatal error on ssr and server bundle doesnt exist', async () => {
+    mockGetNuxtStart(true)
+    jest.spyOn(fs, 'existsSync').mockImplementation(() => false)
+
+    await start()
+
+    expect(consola.fatal).toHaveBeenCalledWith('No SSR build! Please start with `nuxt start --spa` or build using `nuxt build --universal`')
+  })
+})

packages/cli/test/unit/utils.test.js

@@ -0,0 +1,111 @@
+import { consola } from '../utils'
+import * as utils from '../../src/utils'
+
+describe('cli/utils', () => {
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('loadNuxtConfig: defaults', async () => {
+    const argv = {
+      _: ['.'],
+      'config-file': 'nuxt.config.js',
+      universal: true
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.rootDir).toBe(process.cwd())
+    expect(options.mode).toBe('universal')
+    expect(options.server.host).toBe('localhost')
+    expect(options.server.port).toBe(3000)
+    expect(options.server.socket).not.toBeDefined()
+  })
+
+  test('loadNuxtConfig: config-file', async () => {
+    const argv = {
+      _: [__dirname],
+      'config-file': '../fixtures/nuxt.config.js',
+      spa: true
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.testOption).toBe(true)
+    expect(options.rootDir).toBe('/some/path')
+    expect(options.mode).toBe('spa')
+    expect(options.server.host).toBe('nuxt-host')
+    expect(options.server.port).toBe(3001)
+    expect(options.server.socket).toBe('/var/run/nuxt.sock')
+  })
+
+  test('loadNuxtConfig: not-existing config-file', async () => {
+    const argv = {
+      _: [__dirname],
+      'config-file': '../fixtures/nuxt.doesnt-exist.js'
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.testOption).not.toBeDefined()
+
+    expect(consola.fatal).toHaveBeenCalledTimes(1)
+    expect(consola.fatal).toHaveBeenCalledWith(expect.stringMatching(/Could not load config file/))
+  })
+
+  test('loadNuxtConfig: async config-file', async () => {
+    const argv = {
+      _: [__dirname],
+      'config-file': '../fixtures/nuxt.async-config.js',
+      hostname: 'async-host',
+      port: 3002,
+      'unix-socket': '/var/run/async.sock'
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.testOption).toBe(true)
+    expect(options.mode).toBe('supercharged')
+    expect(options.server.host).toBe('async-host')
+    expect(options.server.port).toBe(3002)
+    expect(options.server.socket).toBe('/var/run/async.sock')
+  })
+
+  test('loadNuxtConfig: async config-file with error', async () => {
+    const argv = {
+      _: [__dirname],
+      'config-file': '../fixtures/nuxt.async-error.js'
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.testOption).not.toBeDefined()
+
+    expect(consola.error).toHaveBeenCalledTimes(1)
+    expect(consola.error).toHaveBeenCalledWith(new Error('Async Config Error'))
+    expect(consola.fatal).toHaveBeenCalledWith('Error while fetching async configuration')
+  })
+
+  test('loadNuxtConfig: server env', async () => {
+    const env = process.env
+
+    process.env.HOST = 'env-host'
+    process.env.PORT = 3003
+    process.env.UNIX_SOCKET = '/var/run/env.sock'
+
+    const argv = {
+      _: [__dirname],
+      'config-file': '../fixtures/nuxt.config.js'
+    }
+
+    const options = await utils.loadNuxtConfig(argv)
+    expect(options.server.host).toBe('env-host')
+    expect(options.server.port).toBe('3003')
+    expect(options.server.socket).toBe('/var/run/env.sock')
+
+    process.env = env
+  })
+
+  test('indent', () => {
+    expect(utils.indent(4)).toBe('    ')
+  })
+
+  test('indent custom char', () => {
+    expect(utils.indent(4, '-')).toBe('----')
+  })
+})

packages/cli/test/utils/index.js

@@ -0,0 +1,8 @@
+import consola from 'consola'
+export * from './mocking'
+
+jest.mock('consola')
+
+export {
+  consola
+}

packages/cli/test/utils/mocking.js

@@ -0,0 +1,96 @@
+import Command from '../../src/command'
+
+export const mockGetNuxt = (options, implementation) => {
+  Command.prototype.getNuxt = jest.fn().mockImplementationOnce(() => {
+    return Object.assign({
+      hook: jest.fn(),
+      options
+    }, implementation || {})
+  })
+}
+
+export const mockGetBuilder = (ret) => {
+  const build = jest.fn().mockImplementationOnce(() => {
+    return ret
+  })
+
+  Command.prototype.getBuilder = jest.fn().mockImplementationOnce(() => {
+    return { build }
+  })
+
+  return build
+}
+
+export const mockGetGenerator = (ret) => {
+  const generate = jest.fn()
+  if (ret) {
+    generate.mockImplementationOnce(() => {
+      return ret
+    })
+  }
+
+  Command.prototype.getGenerator = jest.fn().mockImplementationOnce(() => {
+    return { generate }
+  })
+
+  return generate
+}
+
+export const mockGetNuxtStart = (ssr) => {
+  const listen = jest.fn().mockImplementationOnce(() => {
+    return Promise.resolve()
+  })
+  const showReady = jest.fn()
+
+  mockGetNuxt({
+    rootDir: '.',
+    render: {
+      ssr
+    }
+  }, {
+    listen,
+    showReady
+  })
+
+  return { listen, showReady }
+}
+
+export const mockGetNuxtConfig = () => {
+  const spy = jest.fn()
+  Command.prototype.getNuxtConfig = spy
+  return spy
+}
+
+export const mockNuxt = (implementation) => {
+  const Nuxt = function () {}
+  Object.assign(Nuxt.prototype, {
+    hook(type, fn) {
+      if (type === 'watch:fileChanged') {
+        Nuxt.fileChangedHook = fn
+      }
+    },
+    clearHook: jest.fn(),
+    close: jest.fn(),
+    listen: jest.fn().mockImplementationOnce(() => Promise.resolve()),
+    showReady: jest.fn().mockImplementationOnce(() => Promise.resolve())
+  }, implementation || {})
+
+  Command.prototype.importCore = jest.fn().mockImplementationOnce(() => {
+    return { Nuxt }
+  })
+  return Nuxt
+}
+
+export const mockBuilder = (implementation) => {
+  const Builder = function () {}
+  Object.assign(Builder.prototype, {
+    build: jest.fn().mockImplementationOnce(() => Promise.resolve()),
+    unwatch: jest.fn().mockImplementationOnce(() => Promise.resolve()),
+    watchServer: jest.fn().mockImplementationOnce(() => Promise.resolve())
+  }, implementation || {})
+
+  Command.prototype.importBuilder = jest.fn().mockImplementationOnce(() => {
+    return { Builder }
+  })
+  return Builder
+}

yarn.lock

@@ -11088,6 +11088,15 @@ wrap-ansi@^3.0.1:
     string-width "^2.1.1"
     strip-ansi "^4.0.0"
 
+wrap-ansi@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-4.0.0.tgz#b3570d7c70156159a2d42be5cc942e957f7b1131"
+  integrity sha512-uMTsj9rDb0/7kk1PbcbCcwvHUxp60fGDB/NNXpVa0Q+ic/e7y5+BwTxKfQ33VYgDppSwi/FBzpetYzo8s6tfbg==
+  dependencies:
+    ansi-styles "^3.2.0"
+    string-width "^2.1.1"
+    strip-ansi "^4.0.0"
+
 wrappy@1:
   version "1.0.2"
   resolved "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz#b5243d8f3ec1aa35f1364605bc0d1036e30ab69f"