angular.mock.inject causing $injector:moduleerr

I am setting up unit tests using Karma, Require.js, Mocha and Chai. After setting everything up, I have a simple spec file to test a controller and a scope variable.

I know an inject function needs to be used to get $controller service that will instantiate the controller. I am unable to do this. Here is what I have :

define([

    'angular',
    'angularMocks'

], function() {

    describe('MyCtrl', function() {

        var $controller; 

        beforeEach(angular.mock.module('MyApp'));

        // ////////// ATTEMPT 1 

        // beforeEach(angular.mock.inject(function(_$controller_){

        //   $controller = _$controller_;
        // }));

        // ////////// ATTEMPT 2

        // it('should', inject(function(_$rootScope_, _$controller_, _$httpBackend_) {

        // }));

        it('should', function() {

            // ////////// GOAL 

            expect($scope.message).to.equal('hello world');    
        });
    });
});