src-commands-addShow-2-business-logic.js

const max50 = str => str.length <= 50;

module.exports = function addShow({ title, time, host, location }) {
  if (!title || !max50(title)) {
    throw new Error(`title can't be longer than 50 characters`);
  }
  
  if (!(time instanceof Date)) {
    throw new Error(`time must be a date object`);
  }
  
  if (!host || !max50(host)) {
    throw new Error(`host can't be longer than 50 characters`);
  }
  
  if (!location || !max50(location)) {
    throw new Error(`location can't be longer than 50 characters`);
  }
  
  // Data good ... Save a ShowAdded event
};