gistfile1.js

function makeMochaToBrowserScopeCallback ( testKey, sandboxid) {
  'use strict';
	return function mochaToBrowserScopeCallback () {
		var sendToBenchmark = {};
		
		console.log( mocha.globals('runner').suite );

		function applatir (suite) {
			// extraction des résultats des tests
			var title;
			for (var i = 0; i < suite.tests.length; i++) {
				title = suite.tests[i].title;
				title = title.replace(/[^a-zA-Z ]/, '');
				sendToBenchmark[ title ] = (suite.tests[i].state === 'passed')?0:1;
			}

			// on descend encore d'un niveau, recursivité FTW
			if (suite.suites.length > 0) {
				for (i = 0; i < suite.suites.length; i++) {
					applatir(suite.suites[i]);
				}
			}
		}

		applatir(mocha.globals('runner').suite);
		
		console.log( sendToBenchmark );
		window._bTestResults = sendToBenchmark;
		// Beacon the results to Browserscope.
		(function(document) {
			var	newScript = document.createElement('script'),
				firstScript = document.getElementsByTagName('script')[0];
			newScript.src = 'http://www.browserscope.org/user/beacon/' + testKey;
			// + (sandboxid)?'?sandboxid='+sandboxid:'';
			firstScript.parentNode.insertBefore(newScript, firstScript);
		}(document));
	};
}

// USAGE

mocha.run(
  	makeMochaToBrowserScopeCallback(
		'mykey', // JPV key
		'mysandboxId'
	)
);

Here is a snippet of code I wrote to make the bridge between mocha tests and browserscope.
It simply flatten the tests results and convert "passed" to 0 or 1. The method has to be given to mocha.run()