test-Rmd.js

const puppeteer = require('puppeteer');

(async () => {
	var result = 0;
	const browser = await puppeteer.launch({args: ['--no-sandbox', '--disable-setuid-sandbox']});
	console.log("Accessing: " + process.argv[2]);
	const page = await browser.newPage();
	await page.goto(process.argv[2]);
	await page.waitForSelector('#__reactivedoc__ > *, #__reactivedoc__.shiny-output-error')
		.then(() =>  page.$('#__reactivedoc__')
			.then(el => el.getProperty('className'))
			.then(cname => cname.jsonValue())
			.then(json => {
				if (json.includes('shiny-output-error')) {
					console.log('Error in Rmd')
					result = 1
				} else console.log('All is good!')
			})
			.catch(error => {result = 1; console.log('Failed to get element content:' + error)}))
		.catch(error => {result = 1; console.log('Timeout waiting for result:' + error)}) 
	await browser.close();
	process.exit(result);
})();