Promise-compatible tests in 36 lines.

test.js

var descriptions = [];

/* tests here */

function id(x) {
	return x;
}

function describe(described, description) {
	descriptions.push(function () {
		var promises = [];

		description(function it(behaviour, test) {
			var p = new Promise(function (resolve) {
				resolve(test());
			}).catch(id);

			p.name = behaviour;
			promises.push(p);
		});

		return Promise.all(promises).then(function (results) {
			return results.reduce(function (allPassing, result, i) {
				var p = promises[i];

				if (result instanceof Error) {
					console.log('\x1b[31m✘\x1b[0m \x1b[1m%s %s\x1b[0m failed\n%s', described, p.name, result.stack);
					return false;
				}

				console.log('\x1b[32m✔\x1b[0m \x1b[1m%s %s\x1b[0m passed', described, p.name);
				return allPassing;
			}, true);
		});
	});
}

descriptions.reduce(function (first, second) {
	return first.then(function (allPassed) {
		return second().then(function (passed) {
			return allPassed && passed;
		});
	});
}, Promise.resolve(true)).done(function (allPassed) {
	process.exit(!allPassed);
});