nightwatch.config.js

module.exports = {
  selenium: {
    cli_args: {
      'webdriver.chrome.driver': require('chromedriver').path,
      'webdriver.gecko.driver': require('geckodriver').path,
    },
  },
  test_settings: {
    Firefox: {
      desiredCapabilities: {
        browserName: 'firefox',
        acceptInsecureCerts: true,
      },
    },
    FirefoxHeadless: {
      desiredCapabilities: {
        browserName: 'firefox',
        acceptInsecureCerts: true,
        'moz:firefoxOptions': {
          args: ['--headless'],
        },
      },
    },
    ChromeHeadless: {
      desiredCapabilities: {
        browserName: 'chrome',
        javascriptEnabled: true,
        acceptSslCerts: true,
        chromeOptions: {
          args: ['headless'],
        },
      },
    },
  },
}