preprocessor.js

const browserify = require("@cypress/browserify-preprocessor");

module.exports = on => {
  const options = browserify.defaultOptions;
  options.browserifyOptions.transform[1][1].plugins.push([
    "transform-define",
    {
      "process.env.API_URL": process.env.API_URL
    }
  ]);

  on("file:preprocessor", browserify(options));
};