* Gruntfile.js contains configuration for the `testem` task, but could also be in a `testem.json` file. * If you have Istanbul installed as a local dependency, just replace `istanbul` with `node_modules/istanbul/lib/cli.js`. * The collect-coverage.js is some local server that simply saves any data it receives to `coverage.json`. Within the Teste…

collect-coverage.js

var server = require('http').createServer(function(req, res) {
	var body = '';
	req.on('data', function(chunk) {
		body += chunk;
	});
	req.on('end', function() {
		require('fs').writeFile('coverage/data/coverage.json', body, function() {
			res.writeHead(200);
			res.end();
			server.close();
		});
	});
});


module.exports = function(config, data, done) {
	server.listen(8181);
	done();
}

Gruntfile.js

testem: {
	coverage: {
		options: {
			test_page: 'test/index.html#testem,coverage',
			parallel: 2,
			launch_in_ci: ['PhantomJS'],
			on_start: require('./collect-coverage'),
			before_tests: 'istanbul instrument src/ --complete-copy --output src_instrumented/',
			after_tests: 'istanbul report --root coverage/data/ --dir coverage/report/'
		}
	}
},

runner.html

<script>
if (location.hash.indexOf('coverage') > -1) {
	require.config({
		paths: {
			'src': 'src_instrumented'
		}
	});
	jasmineEnv.addReporter(new function(){
		this.jasmineDone = function() {
			$.post('http://localhost:8181/collect', JSON.stringify(window.__coverage__));
		}
	});
}
</script>