create-user.js

const EventEmitter = require('events');

class CreateUser extends EventEmitter {
  constructor({ usersRepository }) {
    super();
    this.usersRepository = usersRepository;
  }

  execute(userData) {
    const user = new User(userData);

    this.usersRepository
      .add(user)
      .then((newUser) => {
        this.emit('SUCCESS', newUser);
      })
      .catch((error) => {
        if(error.message === 'ValidationError') {
          return this.emit('VALIDATION_ERROR', error);
        }

        this.emit('ERROR', error);
      });
  }
}