$httpBackend.flush() method throws Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting

Question

I am trying to unit test my AngularJS application using Karma and Jasmine. I want to mock the $http service. For that, I am using the $httpBackend method. Below is my service that I want to test:

angular.module('MyModule').factory('MyService', function($http, $log, $parse, $q, $timeout, $filter, MyOtherService1, MyOtherService2){
var service = {};
   service.getSomething = function(id){
     return $http.get('/somePath/subpath/' + id);
   }
});

My unit test for this service is:

describe("myTest", function(){
    var myService, $httpBackend, scope, mockMyOtherService1, mockMyOtherService2;

    var myResponse =
    {
        foo:'bar'
    };

    beforeEach(module("MyModule"));

    beforeEach(inject(function(_MyService_, $injector){

        $httpBackend = $injector.get('$httpBackend');
        myService = _MyService_;
        scope = $injector.get('$rootScope').$new();
        mockMyOtherService1 = $injector.get('MyOtherService1');
        mockMyOtherService2 = $injector.get('MyOtherService2');

    }));

    beforeEach(function(){
        //To bypass dependent requests
        $httpBackend.whenGET(/\.html$/).respond(200,'');
    });

    //If I uncomment the below afterEach block, the same error is shown at next line.
    /*afterEach(function() {
         $httpBackend.verifyNoOutstandingExpectation();
         $httpBackend.verifyNoOutstandingRequest();
     });*/

    //This test passes successfully
    it("should check if service is instantiated", function () {
        expect(myService).toBeDefined();
    });

    //This test passes successfully
    it("should expect dependencies to be instantiated", function(){
        expect($httpBackend).toBeDefined();
    });

    //The problem is in this test
    it("should get the getSomething with the provided ID", function() {
        $httpBackend.whenGET('/somePath/subpath/my_123').respond(200,myResponse);            
        var deferredResponse = myService.getSomething('my_123');

        //The error is shown in next line.
        $httpBackend.flush();      

        //If I comment the $httpBackend.flush(), in the next line, the $$state in deferredResponse shows that the Object that I responded with is not set i.e. it does not matches the 'myResponse'.
        expect(deferredResponse).toEqual(myResponse);

    });
});

This is an emergency problem and I need help regarding the same as soon as possible. I will be very grateful for your answer.

Answer 1

You will get a promise from your service. So change your test code to:

//The problem is in this test
it("should get the getSomething with the provided ID", function (done) {
  $httpBackend.expectGET('/somePath/subpath/my_123').respond(200,myResponse);
  var deferredResponse = myService.getSomething('my_123');

  deferredResponse.then(function (value) {
    expect(value.data).toEqual(myResponse);
  }).finally(done);

  $httpBackend.flush();
});

Answer 2

The problem was I needed to inject $location in my spec files even though they are not injected in the services. After injection, all worked well! Hope this helps someone who gets stuck in the same situation.