npm install nightwatch-repl

// nightwatch.conf.js

var repl = require('nightwatch-repl');

module.exports = (function (settings) {
    repl.init(settings);
    ...
    ...
    return settings;
})(require('./nightwatch.json'));

module.exports = {
  'demo test google' : function (browser) {
    browser
      .url('http://google.com')
      .waitForElementPresent('body', 1000);

    // show repl in the console
    browser.repl();
  },

  'part two' : function(client) {
    ....
  }
};