Cypress using .env variables

cypress_env_example.js

/**
 * All files in /cypress/plugins, but only index.js needs to be there
 * With Webpack (and now just modern Node) most imports and exports could be ES6, AFIAK
 * index.js still does a `module.exports`
 *
 * Plugins enable you to tap into, modify, or extend the internal behavior of Cypress.
 * @see https://on.cypress.io/plugins-guide
 */

/**
 * Sets the Cypress test base URL
 *
 * Looks for the `MY_PROJECT_URL`, defaults to an empty string.
 * @param {Object} processEnv The `process.env` object
 * @returns {string} The Cypress base URL
 */
const baseUrl = processEnv => processEnv.MY_PROJECT_URL || '';

module.exports = baseUrl;

/**
 * /cypress/plugins/my-env-vars.js
 * List of custom environment variables; found in `.env` file
 */
module.exports = ['A_PASSWORD', 'A_PATH', 'A_SECRET'];

/**
 * /cypress/plugins/custom-env-vars.js
 *
 * Collects given environment variables into a tidy usable object
 * @param {Object} processEnv The `process.env` object
 * @param {Array} customVars A list of custom environment variables
 */
const customEnvVars = (processEnv, customVars = []) =>
  customVars.reduce((acc, envVar) => {
    acc[envVar] = processEnv[envVar];
    return acc;
  }, {});

module.exports = customEnvVars;

/**
 * /cypress/plugins/index.js
 * Allows reading of environment variables from `.env` file
 * @see github.com/motdotla/dotenv
 * For variable expansion:
 * @see github.com/motdotla/dotenv-expand
 */
require('dotenv').config();

const baseUrl = require('./base-url');
const myEnvVars = require('./my-env-vars');
const customEnvironmentVariables = require('./custom-env-vars');

module.exports = (on, config) => {
  // `on` is used to hook into various events Cypress emits
  // `config` is the resolved Cypress config

  // Set Cypress base URL
  config.baseUrl = baseUrl(process.env);

  // Set Cypress environment variables needed to run the tests
  config.env = customEnvironmentVariables(process.env, myEnvVars);

  return config;
};