old_contents: "use strict";
  
  class DummyRobot {
  
      constructor(props) {
          this.respond = (regix, callback) => {
              if (regix.test(this.inputMessage)) {
                  var msg = {
                      match: regix.exec(this.inputMessage),
                      text: this.inputMessage,
                      send: this.captureSend,
                      emit: this.captureEmit,
                  }
                  callback(msg);
              }
          };
  
          this.hear = (regix, callback) => {
              respond(regix, callback);
          };
  
          this.captureSend = (message) => {
              this._output = message;
          };
  
          this.captureEmit = (message) => {
              captureSend(message);
          };
  
          this.testRun = (extendedScript, inputMessage) => {
              this.inputMessage = inputMessage;
              extendedScript(this);
              return this._output;
          };
      }
  }
  
  module.exports = DummyRobot;
new_contents: "use strict";
  
  class DummyRobot {
  
      constructor(props) {
          this.respond = (regix, callback) => {
              if (regix.test(this.inputMessage)) {
                  var msg = {
                      match: regix.exec(this.inputMessage),
                      text: this.inputMessage,
                      send: this.captureSend,
                      emit: this.captureEmit,
                  }
                  callback(msg);
              }
          };
  
          this.hear = (regix, callback) => {
              this.respond(regix, callback);
          };
  
          this.captureSend = (message) => {
              this._output = message;
          };
  
          this.captureEmit = (message) => {
              captureSend(message);
          };
  
          this.testRun = (extendedScript, inputMessage) => {
              this.inputMessage = inputMessage;
              extendedScript(this);
              return this._output;
          };
      }
  }
  
  module.exports = DummyRobot;
subject: add 'this'