feat(cli): add help command (#4248)

* add commands/help

* simply cmds in run()

* refinement

* simply cmds in run() (2)

* simply cmds in run() (3)

* lint

* cmd.showHelp()

* check for cmd / uknown cmd

* final fix

* fixes

* remove Set

* Add NuxtCommand.load()

* updated tests

* lint

packages/cli/src/command.js

@@ -2,6 +2,7 @@ import parseArgs from 'minimist'
 import { name, version } from '../package.json'
 import { loadNuxtConfig } from './utils'
 import { indent, foldLines, startSpaces, optionSpaces } from './formatting'
+import * as commands from './commands'
 import * as imports from './imports'
 
 export default class NuxtCommand {
@@ -13,6 +14,17 @@ export default class NuxtCommand {
     this._run = run
   }
 
+  static async load(name) {
+    // So eslint doesn't complain about lookups
+    const _commands = { ...commands }
+    if (name in _commands) {
+      const cmd = await _commands[name]().then(m => m.default)
+      return NuxtCommand.from(cmd)
+    } else {
+      // TODO dynamic module loading
+    }
+  }
+
   static from(options) {
     if (options instanceof NuxtCommand) {
       return options

packages/cli/src/commands/help.js

@@ -0,0 +1,20 @@
+import consola from 'consola'
+import NuxtCommand from '../command'
+
+export default {
+  name: 'help',
+  description: 'Shows help for <command>',
+  usage: 'help <command>',
+  async run(cmd) {
+    const argv = cmd.getArgv()._
+    const name = argv[0] || null
+    const command = await NuxtCommand.load(name)
+    if (command) {
+      command.showHelp()
+    } else if (name === null) {
+      consola.info(`Please specify a command`)
+    } else {
+      consola.info(`Unknown command: ${name}`)
+    }
+  }
+}

packages/cli/src/commands/index.js

@@ -2,3 +2,4 @@ export const start = () => import('./start')
 export const dev = () => import('./dev')
 export const build = () => import('./build')
 export const generate = () => import('./generate')
+export const help = () => import('./help')

packages/cli/src/run.js

@@ -6,9 +6,7 @@ import { indent, foldLines, startSpaces, optionSpaces } from './formatting'
 
 async function listCommands(_commands) {
   _commands = await Promise.all(
-    Object.keys(_commands).map((cmd) => {
-      return _commands[cmd]().then(m => m.default)
-    })
+    Object.keys(_commands).map(cmd => NuxtCommand.load(cmd))
   )
   let maxLength = 0
   const commandsHelp = []
@@ -33,21 +31,14 @@ async function listCommands(_commands) {
 
 export default function run() {
   const defaultCommand = 'dev'
-
-  const cmds = new Set([
-    defaultCommand,
-    'build',
-    'start',
-    'generate'
-  ])
-
   let cmd = process.argv[2]
 
-  if (cmds.has(cmd)) {
+  const _commands = { ...commands }
+  if (_commands[cmd]) {
     process.argv.splice(2, 1)
   } else {
     if (process.argv.includes('--help') || process.argv.includes('-h')) {
-      listCommands({ ...commands }).then(() => process.exit(0))
+      listCommands(_commands).then(() => process.exit(0))
       return
     }
     cmd = defaultCommand
@@ -58,9 +49,7 @@ export default function run() {
     dev: cmd === 'dev'
   })
 
-  return commands[cmd]() // eslint-disable-line import/namespace
-    .then(m => m.default)
-    .then(options => NuxtCommand.from(options))
+  return NuxtCommand.load(cmd)
     .then(command => command.run())
     .catch((error) => {
       consola.fatal(error)

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

@@ -19,3 +19,22 @@ exports[`cli/command builds help text 1`] = `
 
 "
 `;
+
+exports[`cli/command loads command from name 1`] = `
+"  Usage: nuxt dev <dir> [options]
+
+  Start the application in development mode (e.g. hot-code reloading, error reporting)
+
+  Options:
+
+    --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
+    --port, -p         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
+
+"
+`;

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

@@ -117,6 +117,11 @@ describe('cli/command', () => {
     expect(cmd._getHelp()).toMatchSnapshot()
   })
 
+  test('loads command from name', async () => {
+    const cmd = await Command.load('dev')
+    expect(cmd._getHelp()).toMatchSnapshot()
+  })
+
   test('show version prints to stdout and exits', () => {
     jest.spyOn(process.stdout, 'write').mockImplementation(() => {})
     jest.spyOn(process, 'exit').mockImplementationOnce(code => code)