karma-electron/lib/electron-launcher.js

// When we run into an uncaught exception, fail hard
// DEV: Without this line, Karma can hang indefinitely
process.on('uncaughtException', function handleUncaughtException (err) {
  throw err;
});

// Load in our dependencies
var assert = require('assert');
var path = require('path');
var app = require('electron').app;
var BrowserWindow = require('electron').BrowserWindow;
var program = require('commander');

// Set up our CLI parser
program.name = 'electron-launcher';
program.option('--user-data-dir [dir]', 'Directory to store user data');
program.option('--show', 'Boolean to make the window visible');
program.option('--stdin-options', 'Load additional options via `stdin`');
program.option('--default-user-agent', 'Boolean when spefified uses default user agent');
program.option('--url [url]', 'URL to load page at');
program.option('--require [filepath]', 'Path to main process file to require');
program.allowUnknownOption();

// Parse and assert our arguments
program.parse(process.argv);
assert(program.userDataDir, 'Expected `--user-data-dir` to be provided but it was not.');
assert(program.url, 'Expected `--url` to be provided but it was not.');

// When all windows are closed, exit out
app.on('window-all-closed', function handleWindowsClosed () {
  app.quit();
});

// Update `userData` before Electron loads
// DEV: This prevents cookies/localStorage from contaminating across apps
app.setPath('userData', program.userDataDir);

// If we have another file to require, then load it
// DEV: We use `path.resolve` to resolve relative paths from working directory
//   Otherwise, a `require('./foo')` would load relative to this file
if (program.require) {
  require(path.resolve(program.require));
}

// When Electron is done loading, launch our applicaiton
app.on('ready', function handleReady () {
  // If we have `stdin` options, then load them in
  //   https://nodejs.org/docs/latest-v12.x/api/process.html#process_process_stdin
  // DEV: We perform this after `app.on('ready')` as we want to handle all those actions synchrously
  if (program.stdinOptions) {
    var stdinContent = '';
    process.stdin.setEncoding('utf8');
    process.stdin.on('readable', function handleReadable () {
      // Use a loop to make sure we read all available data.
      while (true) {
        var stdinChunk = process.stdin.read();
        if (stdinChunk === null) {
          break;
        }
        stdinContent += stdinChunk;
      }
    });
    process.stdin.on('end', function handleEnd () {
      var stdinOptions = JSON.parse(stdinContent);
      Object.assign(program, stdinOptions);
      launchBrowserWindow();
    });
  // Otherwise, launch our browser window
  } else {
    // DEV: We run `launchBrowserWindow` asynchronously to match async behavior in both cases
    process.nextTick(launchBrowserWindow);
  }

  function launchBrowserWindow() { /* jshint ignore:line */
    // Create our browser window
    var browserWindowOptions = Object.assign({
      show: false
    }, program.browserWindowOptions);
    if (program.show !== undefined) {
      browserWindowOptions.show = !!program.show;
    }
    var browserWindow = new BrowserWindow(browserWindowOptions);

    var loadURLOptions = Object.assign({}, program.loadURLOptions);
    if (program.defaultUserAgent !== true) {
      // Set a custom User-Agent for better logging
      // https://github.com/atom/electron/blob/v0.36.9/docs/api/browser-window.md#winloadurlurl-options
      // https://github.com/atom/electron/blob/v0.36.9/docs/api/web-contents.md#webcontentsloadurlurl-options
      // DEV: Default would be "Chrome 47.0.2526 (Linux 0.0.0)"
      //   https://github.com/karma-runner/karma/blob/v0.13.21/lib/browser.js#L25
      //   https://github.com/karma-runner/karma/blob/v0.13.21/lib/helper.js#L7-L11
      // Example: Electron 0.36.9 (Node.js 5.1.1)
      loadURLOptions.userAgent = 'Electron ' + process.versions.electron + ' (Node ' + process.versions.node + ')';
    }
    browserWindow.loadURL(program.url, loadURLOptions);
  }
});