Michael Bromley Michael Bromley - 5 months ago 24
AngularJS Question

Unit testing the output of $sce.trustAsHtml in Angular

I am writing a REST app in Angular and I want to write unit tests for it (of course!). I have a controller which gets a list of blog posts from a REST service in json and puts the summaries into the $scope, so I can display them in the view.

At first the blog posts were just displaying as text ie

<p>Blog body</p>
, rather than rendering as parsed HTML, until I discovered that you can use ng-bind-html in conjunction with the $sce service. This now works fine in terms of displaying the blog posts correctly.

The problem arises when unit testing. I am trying to mock a json response with some HTML and then test that my controller is correctly dealing with the HTML. Here is my code:

Controller



.controller( 'HomeCtrl', function HomeController( $scope, $http, $sce ) {
$scope.posts = {};
$http.get('../drupal/node.json').success(function (data) {
var posts;
posts = data.list;

for(var i = 0; i < posts.length; i ++) {
posts[i].previewText = $sce.trustAsHtml(posts[i].body.summary);
posts[i].created = posts[i].created + '000'; // add milliseconds so it can be properly formatted
}
$scope.posts = posts;
});
})


unit test



describe('HomeCtrl', function() {
var $httpBackend, $rootScope, $sce, createController;

beforeEach(inject(function ($injector) {
// Set up the mock http service responses
$httpBackend = $injector.get('$httpBackend');

// Get hold of a scope (i.e. the root scope)
$rootScope = $injector.get('$rootScope');
// The $controller service is used to create instances of controllers
var $controller = $injector.get('$controller');

$sce = $injector.get('$sce');

createController = function() {
return $controller('HomeCtrl', {
'$scope': $rootScope
});
};
}));

it('should get a list of blog posts', function() {
var rawResponse = {
"list": [
{
"body": {
"value": "\u003Cp\u003EPost body.\u003C\/p\u003E\n",
"summary": "\u003Cp\u003ESummary.\u003C\/p\u003E\n"
},
"created": "1388415860"
}
]};
var processedResponse = [{
"body": {
"value": "\u003Cp\u003EPost body.\u003C\/p\u003E\n",
"summary": "\u003Cp\u003ESummary.\u003C\/p\u003E\n"
},
"created": "1388415860000",
previewText: $sce.trustAsHtml("\u003Cp\u003ESummary.\u003C\/p\u003E\n")
}];

$httpBackend.when('GET', '../drupal/node.json').respond(rawResponse);
$httpBackend.expectGET("../drupal/node.json").respond(rawResponse);
var homeCtrl = createController();
expect(homeCtrl).toBeTruthy();
$httpBackend.flush();
expect($rootScope.posts).toEqual(processedResponse);
});
});


When I run the above through the Karma test runner, I get the following response:

Chrome 31.0.1650 (Windows) home section HomeCtrl should get a list of blog posts FAILED
Expected [ { body : { value : '<p>Post body.</p>
', summary : '<p>Summary.</p>
' }, created : '1388415860000', previewText : { $$unwrapTrustedValue : Function } } ] to equal [ { body
: { value : '<p>Post body.</p>
', summary : '<p>Summary.</p>
' }, created : '1388415860000', previewText : { $$unwrapTrustedValue : Function } } ].


I suspect the problem is due to the fact that
$sce.trustAsHtml
returns an object containing a function, rather than a string.

My question is, firstly, am I approaching this problem in the correct way?

Secondly, if so, how should I go about testing the output of
$sce.trustAsHtml
?

Answer

Since the answer given by michael-bromley didn't work for me I want to point out another solution. In my case I was using a filter that wraps each occurrence of a string in another string with a span that has a class of 'highlight'. In other words, I want words to be highlighted. Here is the code:

angular.module('myModule').filter('highlight', function ($sce) {
    return function (input, str) {
        return $sce.trustAsHtml((input || '').replace(new RegExp(str, 'gi'), '<span class=\"highlighted\">$&</span>'));
    };
});

I use the $sce service to trust the resulting value as HTML. To test this I need to use the $$unwrapTrustedValue function on the resulting value to get my test working:

it('01: should add a span with class \'highlight\' around each mathing string.', inject(function ($filter) {
    // Execute
    var result = $filter('highlight')('this str contains a str that will be a highlighted str.', 'str');

    // Test
    expect(result.$$unwrapTrustedValue()).toEqual('this <span class="highlighted">str</span> contains a <span class="highlighted">str</span> that will be a highlighted <span class="highlighted">str</span>.'); 
}));

UPDATE:

As @gugol kindly pointed out it is preferred not to use Angular internal methods like $$unwrapTrustedValue. A better approach is to use the public getTrustedHtml method on the $sce service. Like so:

it('01: should add a span with class \'highlight\' around each mathing string.', inject(function ($sce, $filter) {
    // Execute
    var result = $filter('highlight')('this str contains a str that will be a highlighted str.', 'str');

    // Test
    expect($sce.getTrustedHtml(result)).toEqual('this <span class="highlighted">str</span> contains a <span class="highlighted">str</span> that will be a highlighted <span class="highlighted">str</span>.');
}));
Comments