karma-example.js

describe('Home', function () {                                                  
    var HomeCtrl, $httpBackend;                                                 
                                                                                
    beforeEach(angular.mock.module('app'));                                     
                                                                                
    beforeEach(angular.mock.inject(function ($controller, _$httpBackend_) {     
        $httpBackend = _$httpBackend_;                                          
                                                                                
        $httpBackend.when("GET", "/things.json")                                
            .respond([4,5,6]);                                                  
                                                                                
        HomeCtrl = $controller("HomeCtrl");                                     
    }));                                                                        
                                                                                
    it("should have the first thing", function () {                             
        $httpBackend.flush();                                                   
        expect(HomeCtrl.thing).toBe(4);                                         
    });                                                                         
});

tested-example.js

angular.module('app', [])                                                       
.factory('thing', function ($http) {                                            
    var things = [];                                                            
                                                                                
    return {                                                                    
        getThings: function () {                                                
            return things;                                                      
        },                                                                      
        fetchThings: function () {                                              
            return $http.get("/things.json").success(function (serverThings) {  
                things = serverThings;                                          
            });                                                                 
        },                                                                      
    };                                                                          
})                                                                              
.controller('HomeCtrl', function (thing) {                                      
    var home = this;                                                            
                                                                                
    thing.fetchThings().success(function () {                                   
        home.thing = thing.getThings()[0];                                      
    });                                                                         
});