feat: add bundled app validation to ensure that package.json and main entry point exist

src/common.js

@@ -1,6 +1,8 @@
 'use strict'
 
+const debug = require('debug')('electron-packager')
 const filenamify = require('filenamify')
+const fs = require('fs-extra')
 const metadata = require('../package.json')
 const os = require('os')
 const path = require('path')
@@ -85,6 +87,36 @@ module.exports = {
   normalizePath: function normalizePath (pathToNormalize) {
     return pathToNormalize.replace(/\\/g, '/')
   },
+  /**
+   * Validates that the application directory contains a package.json file, and that there exists an
+   * appropriate main entry point file, per the rules of the "main" field in package.json.
+   *
+   * See: https://docs.npmjs.com/cli/v6/configuring-npm/package-json#main
+   *
+   * @param appDir - the directory specified by the user
+   * @param bundledAppDir - the directory where the appDir is copied to in the bundled Electron app
+   */
+  validateElectronApp: async function validateElectronApp (appDir, bundledAppDir) {
+    debug('Validating bundled Electron app')
+    debug('Checking for a package.json file')
+
+    const bundledPackageJSONPath = path.join(bundledAppDir, 'package.json')
+    if (!(await fs.pathExists(bundledPackageJSONPath))) {
+      const originalPackageJSONPath = path.join(appDir, 'package.json')
+      throw new Error(`Application manifest was not found. Make sure "${originalPackageJSONPath}" exists and does not get ignored by your ignore option`)
+    }
+
+    debug('Checking for the main entry point file')
+    const packageJSON = await fs.readJson(bundledPackageJSONPath)
+    const mainScriptBasename = packageJSON.main || 'index.js'
+    const mainScript = path.resolve(bundledAppDir, mainScriptBasename)
+    if (!(await fs.pathExists(mainScript))) {
+      const originalMainScript = path.join(appDir, mainScriptBasename)
+      throw new Error(`The main entry point to your app was not found. Make sure "${originalMainScript}" exists and does not get ignored by your ignore option`)
+    }
+
+    debug('Validation complete')
+  },
 
   hostInfo: function hostInfo () {
     return `Electron Packager ${metadata.version}\n` +

src/platform.js

@@ -110,6 +110,7 @@ class App {
 
   async buildApp () {
     await this.copyTemplate()
+    await common.validateElectronApp(this.opts.dir, this.originalResourcesAppDir)
     await this.asarApp()
   }
 

test/basic.js

@@ -303,3 +303,29 @@ test.serial('electronZipDir: ZIP file does not exist', util.testSinglePlatform(a
 
   await t.throwsAsync(async () => packager(opts), { message: /Electron ZIP file does not exist/ })
 }))
+
+test('validateElectronApp succeeds on a well-formed Electron app containing a main field', async t => {
+  await t.notThrowsAsync(async () => await common.validateElectronApp('original-dir', util.fixtureSubdir('validate-success-with-main')))
+})
+
+test('validateElectronApp succeeds on a well-formed Electron app without a main field', async t => {
+  await t.notThrowsAsync(async () => await common.validateElectronApp('original-dir', util.fixtureSubdir('validate-success-without-main')))
+})
+
+test('validateElectronApp fails on an Electron app without package.json', async t => {
+  await t.throwsAsync(async () => await common.validateElectronApp('original-dir', util.fixtureSubdir('validate-failure-without-package-json')), {
+    message: `Application manifest was not found. Make sure "${path.join('original-dir', 'package.json')}" exists and does not get ignored by your ignore option`
+  })
+})
+
+test('validateElectronApp fails on an Electron app with a package.json with a main field missing main entry point', async t => {
+  await t.throwsAsync(async () => await common.validateElectronApp('original-dir', util.fixtureSubdir('validate-failure-without-main-or-index')), {
+    message: `The main entry point to your app was not found. Make sure "${path.join('original-dir', 'index.js')}" exists and does not get ignored by your ignore option`
+  })
+})
+
+test('validateElectronApp fails on an Electron app with a package.json without a main field missing main entry point', async t => {
+  await t.throwsAsync(async () => await common.validateElectronApp('original-dir', util.fixtureSubdir('validate-failure-with-main-without-entry-point')), {
+    message: `The main entry point to your app was not found. Make sure "${path.join('original-dir', 'main.js')}" exists and does not get ignored by your ignore option`
+  })
+})

test/fixtures/validate-failure-with-main-without-entry-point/package.json

@@ -0,0 +1 @@
+{"main": "main.js"}

test/fixtures/validate-failure-without-main-or-index/package.json

@@ -0,0 +1 @@
+{}

test/fixtures/validate-success-with-main/package.json

@@ -0,0 +1 @@
+{"main": "main.js"}

test/fixtures/validate-success-without-main/package.json

@@ -0,0 +1 @@
+{}