code: function normalizeOptions(options) {
      const pathToBin = path.join(process.cwd(), 'node_modules', '.bin');
      const pathName = /^win/.test(process.platform) ? 'Path' : 'PATH';
      const newPath = pathToBin + path.delimiter + process.env[pathName];
  
      return _.extend({
          elmTest: 'elm-test',
          args: [],
          verbose: false,
          errorMessage: 'Running tests for `<%= file.path %>` failed with exit code <%= error.code %>',
          quiet: false,
          cwd: process.cwd(),
          env: _.extend(process.env, _.fromPairs([[pathName, newPath]]), options ? options.env : undefined),
      }, options);
  }
docs: some of the following code is based on https://github.com/sun-zheng-an/gulp-shell/blob/4de040ab0b96d05aba5d6e054b61f4a3ab3227e6/index.js, Copyright (c) 2014 Sun Zheng'an, under the MIT license