feat: allow vue add to work with plugins without a generator (#1032)

packages/@vue/cli/lib/add.js

@@ -2,6 +2,7 @@ const chalk = require('chalk')
 const invoke = require('./invoke')
 const { loadOptions } = require('./options')
 const { installPackage } = require('./util/installDeps')
+const { resolveModule } = require('./util/module')
 const {
   log,
   error,
@@ -26,7 +27,12 @@ async function add (pluginName, options = {}, context = process.cwd()) {
   log(`${chalk.green('✔')}  Successfully installed plugin: ${chalk.cyan(packageName)}`)
   log()
 
-  invoke(pluginName, options, context)
+  const generatorPath = resolveModule(`${packageName}/generator`, context)
+  if (generatorPath) {
+    invoke(pluginName, options, context)
+  } else {
+    log(`Plugin ${packageName} does not have a generator to invoke`)
+  }
 }
 
 module.exports = (...args) => {

packages/@vue/cli/lib/invoke.js

@@ -3,11 +3,11 @@ const path = require('path')
 const execa = require('execa')
 const chalk = require('chalk')
 const globby = require('globby')
-const resolve = require('resolve')
 const inquirer = require('inquirer')
 const Generator = require('./Generator')
 const { loadOptions } = require('./options')
 const { installDeps } = require('./util/installDeps')
+const { loadModule } = require('./util/module')
 const {
   log,
   error,
@@ -18,16 +18,6 @@ const {
   resolvePluginId
 } = require('@vue/cli-shared-utils')
 
-function load (request, context) {
-  let resolvedPath
-  try {
-    resolvedPath = resolve.sync(request, { basedir: context })
-  } catch (e) {}
-  if (resolvedPath) {
-    return require(resolvedPath)
-  }
-}
-
 async function readFiles (context) {
   const files = await globby(['**'], {
     cwd: context,
@@ -75,15 +65,15 @@ async function invoke (pluginName, options = {}, context = process.cwd()) {
     )
   }
 
-  const pluginGenerator = load(`${id}/generator`, context)
+  const pluginGenerator = loadModule(`${id}/generator`, context)
   if (!pluginGenerator) {
     throw new Error(`Plugin ${id} does not have a generator.`)
   }
 
   // resolve options if no command line options are passed, and the plugin
   // contains a prompt module.
   if (!Object.keys(options).length) {
-    const pluginPrompts = load(`${id}/prompts`, context)
+    const pluginPrompts = loadModule(`${id}/prompts`, context)
     if (pluginPrompts) {
       options = await inquirer.prompt(pluginPrompts)
     }

packages/@vue/cli/lib/util/module.js

@@ -0,0 +1,16 @@
+const resolve = require('resolve')
+
+exports.resolveModule = function resolveModule (request, context) {
+  let resolvedPath
+  try {
+    resolvedPath = resolve.sync(request, { basedir: context })
+  } catch (e) {}
+  return resolvedPath
+}
+
+exports.loadModule = function loadModule (request, context) {
+  const resolvedPath = exports.resolveModule(request, context)
+  if (resolvedPath) {
+    return require(resolvedPath)
+  }
+}