A continuación se muestra mi onprepare y reporteros. Cuando accedo a result_path en los reporteros, obtuve el valor como indefinido.

 onPrepare: function (config, capabilities) { today = new Date() date = today.getDate() time = date + "_" + today.getHours() + "hrs_" + today.getMinutes() + "mins_" + today.getSeconds() + "secs" result_path = './execution_time_'+ time if (!fs.existsSync(result_path)) { fs.mkdirSync(result_path); } }, reporters: [['timeline', { outputDir: result_path+'/', fileName: 'timeliner-reporter.html', embedImages: true, images: { quality: 80, resize: false, reductionRation: 2 }, screenshotStrategy:'before:click' }]],