Checks 2nd parameter of the notify() method to be a function

lib/utils.js

@@ -162,6 +162,10 @@ module.exports.mapToMac = function (options) {
 module.exports.actionJackerDecorator = function (emitter, options, fn, mapper) {
   options = clone(options);
   fn = fn || function (err, data) {};
+
+  if (typeof fn !== "function")
+    throw new TypeError('The second argument must be a function callback. You have passed '+ typeof fn);
+
   return function (err, data) {
 
     var resultantData = data;

notifiers/notifysend.js

@@ -29,6 +29,9 @@ NotifySend.prototype.notify = function (options, callback) {
   options = cloneDeep(options || {});
   callback = callback || function () {};
 
+  if (typeof callback !== "function")
+    throw new TypeError('The second argument must be a function callback. You have passed '+ typeof callback);
+
   if (typeof options === 'string') options = {
       title: 'node-notifier',
       message: options

test/index.js

@@ -8,6 +8,22 @@ describe('constructors', function(){
     should(notifier.notify).be.ok;
   });
 
+  it('should expect only a function callback as second parameter', function () {
+    var cb = function (err, data) {};
+    var data = { 'title': 'My notification' };
+
+    should(notifier.notify(data, cb)).be.ok;
+  });
+
+  it('should throw error when second parameter is not a function', function () {
+    var wrongParamOne = 200;
+    var wrongParamTwo = 'meaningless string';
+    var data = { 'title': 'My notification' };
+
+    notifier.notify.bind(notifier, data, wrongParamOne).should.throw(/^The second argument/);
+    notifier.notify.bind(notifier, data, wrongParamTwo).should.throw(/^The second argument/);
+  });
+
   it('should expose a default selected constructor function', function () {
     should(notifier instanceof notifier.Notification).be.ok;
   });