fail mocha upon loader fail

related to #885

test/all.js

@@ -38,7 +38,15 @@ function loadSingleTest(test) {
 	var moduleId = path.relative(src, path.resolve(test)).replace(/\.js$/, '');
 
 	return function (cb) {
+		var onExit = function () {
+			console.error('Failed to load test.');
+			process.exit(1);
+		};
+
+		process.once('exit', onExit);
+
 		define([moduleId], function () {
+			process.removeListener('exit', onExit);
 			cb(null);
 		});
 	};
@@ -50,8 +58,16 @@ function loadClientTests(cb) {
 			return file.replace(/\.js$/, '');
 		});
 
+		var onExit = function () {
+			console.error('Failed to load all client tests.');
+			process.exit(1);
+		};
+
+		process.once('exit', onExit);
+
 		// load all modules
 		define(modules, function () {
+			process.removeListener('exit', onExit);
 			cb(null);
 		});
 	});
@@ -65,7 +81,15 @@ function loadPluginTests(cb) {
 			return 'extensions/' + file.replace(/\.js$/, '');
 		});
 
+		var onExit = function () {
+			console.error('Failed to load plugin tests.');
+			process.exit(1);
+		};
+
+		process.once('exit', onExit);
+
 		define(modules, function() {
+			process.removeListener('exit', onExit);
 			cb();
 		});
 	});