vue-cli/packages/@vue/cli/lib/inspect.js

const fs = require('fs')
const path = require('path')
const execa = require('execa')
const resolve = require('resolve')

module.exports = function inspect (paths, mode) {
  const cwd = process.cwd()
  let servicePath
  try {
    servicePath = resolve.sync('@vue/cli-service', { basedir: cwd })
  } catch (e) {
    const { error } = require('@vue/cli-shared-utils')
    error(`Failed to locate @vue/cli-service. Make sure you are in the right directory.`)
    process.exit(1)
  }
  const binPath = path.resolve(servicePath, '../../bin/vue-cli-service.js')
  if (fs.existsSync(binPath)) {
    execa('node', [
      binPath,
      'inspect',
      ...(mode ? ['--mode', mode] : []),
      ...paths
    ], { cwd, stdio: 'inherit' })
  }
}