Getting “Unexpected request” error when running Karma unit test in an AngularJS app

Question

I'm trying to write a unit test for a controller which fetches article details using $http service.

Controller:

 .controller('ArticleDetailCtrl',function($scope, Article, $routeParams, API_URL, ARTICLE_URL, $http, $sce){

    $scope.url = API_URL + ARTICLE_URL + '/' + $routeParams.articleId;

    $http.get($scope.url).then(function(response) {
        //console.log(response.data);
        $scope.heading = response.data.Headline;
        $scope.rawBody = response.data.Body;
        $scope.body = $sce.trustAsHtml($scope.rawBody);
        $scope.image = response.data.Assets[0].URL;
    });   
    });

Unit test:

'use strict';

describe('Controller: Article', function () {

    var scope,
        $httpBackend,
        articleEndpoint;



    // load the controller's module
    beforeEach(module('myApp'));


    describe('ArticleDetailCtrl', function () {

        var ArticleDetailCtrl,
            jsonObject,
            ArticleId = '123';

        // Initialize the controller and a mock scope
        beforeEach(inject(function ($controller, $rootScope, _$httpBackend_, Article, API_URL, ARTICLE_URL) {

            scope = $rootScope.$new();
            ArticleDetailCtrl = $controller('ArticleDetailCtrl', { $scope: scope });
            $httpBackend =  _$httpBackend_;
            articleEndpoint = API_URL + ARTICLE_URL + '/' + ArticleId;

            jsonObject = {
                'Headline': 'Headline',
                'Body': '<p>Body</p>',
                'Assets': [
                    {
                        'URL': 'path/to/image/article1.jpg'
                    }
                ]
            };

            $httpBackend.when('GET', articleEndpoint).respond(jsonObject);
        }));

        afterEach(function() {
            $httpBackend.verifyNoOutstandingExpectation();
            $httpBackend.verifyNoOutstandingRequest();
        });

        it('should fetch article details from the API', function () {
            //expect(scope.articles.length).toEqual(3);

            $httpBackend.expectGET(articleEndpoint);
            $httpBackend.flush();
        });

    });    

});

But I keep on getting the following error:

Error: Unexpected request: GET http://localhost:3000/api/articles/undefined
Expected GET http://localhost:3000/api/articles/123
    at $httpBackend (/Users/gill/Documents/projects/angularjs-test/app/bower_components/angular-mocks/angular-mocks.js:1179)
    at sendReq (/Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:8181)
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:7921
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:11319
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:11405
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:12412
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular/angular.js:12224
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular-mocks/angular-mocks.js:1438
    at /Users/gill/Documents/projects/angularjs-test/test/spec/controllers/article.js:77
Error: Unsatisfied requests: GET http://localhost:3000/api/articles/123
    at /Users/gill/Documents/projects/angularjs-test/app/bower_components/angular-mocks/angular-mocks.js:1472
    at /Users/gill/Documents/projects/angularjs-test/test/spec/controllers/article.js:65

This is the first time am writing unit tests which I followed along by reading some tutorials. I don't know what am I doing wrong?

Answer 1

Your problem is a simple, but a common one.

When you write your Jasmine / Karma unit tests, creating your controllers are almost automatic using the $controller service. That means, for the most part, you can say from your unit test

$controller('ArticleDetailCtrl')

And AngularJS will figure out its dependent services, inject them and create an instance of the controller for you to unit test.

There is one exception to this:

AngularJS does not know how to inject context specific services like $scope and $routeParams, which change based on the HTML structure and the URL for each instance of the controller.

I notice in your unit test you create the controller as

ArticleDetailCtrl = $controller('ArticleDetailCtrl', { $scope: scope });

So at this point, you tell AngularJS what object to use when the controller asks for $scope as a dependent service. But in your controller, you also inject $routeParams. And based on its articleId you create the URL for the request.

So if you change your controller instantiation code to:

ArticleDetailCtrl = $controller('ArticleDetailCtrl', { 
    $scope: scope, 
    $routeParams: articleId: ArticleId
});

That should now create the correct URL (instead of using undefined for articleId, which was the error)

Let me know if that helps.