javascript - 如何对 AngularJS 服务/工厂进行单元测试

Question

我已经使用 AngularJS 进行开发一段时间了，我写的东西很有效，但我知道我已经到了想要在我的 AngularJS 代码上运行单元测试的地步。

我创建了一个非常简单的服务，它将在页面上注入(inject)样式表， 请参阅下面的示例代码:

var OfficeSuiteStylesheetInjectorModule = angular.module('OfficeSuiteStylesheetInjectorModule', []);

OfficeSuiteStylesheetInjectorModule.factory('stylesheetInjectorService', ['$q', function($q) {
    // Returns the service itself.
    return {
        inject: function(id, uri) {
            var deferred = $q.defer();

            // Embed the stylesheet into the page, but only when it's non-existing.
            if (!angular.element('#' + id).length) {
                    var link = StylesheetFactory.Create(id, uri);
                    {
                        link.onload = deferred.resolve;
                        angular.element('head').append(link);
                    }

                    return deferred.promise;
                }
        }
    }
}]);

这不是一个大服务，它只是依赖于 $q 的 promise ，以便我可以在样式表嵌入到页面中时运行额外的逻辑。

现在，我正在使用 Jasmine(我对此还很陌生)来测试我的 JavaScript 代码，我想测试这个模块。

我有一个骨架:

// Tests for the angular 'StylesheetInjectorService'.
describe('StylesheetInjectorService', function() {
    var stylesheetInjectorService = {};

    // This code is executed before every test.
    beforeEach(function() {
        // Tells jamine that the module we're working on is the 'OfficeSuiteStylesheetInjectorModule'.
        angular.module('OfficeSuiteStylesheetInjectorModule');
    });

    // Ensures that it injects a stylesheet element into the page.
    it('Should inject a stylesheet element into the page.', function() {
        // How to test here that the stylesheet is injected?
    });
  });
});

如何在页面中注入(inject)服务并确保样式表已加载？

编辑:加载服务现在可以运行:

beforeEach(module('OfficeSuiteStylesheetInjectorModule'));

// This code is executed before every test.
beforeEach(function() {

    // Inject the required dependencies into the page.
    inject(function($injector) {
        stylesheetInjectorService = $injector.get('stylesheetInjectorService');
    });
});

但是同样的问题仍然悬而未决。如何测试页面中是否嵌入了样式表？

非常感谢任何帮助。

亲切的问候

Answer 1

要编写将样式表附加到 angular.element('head') 的规范，我会稍微更改逻辑以将其附加到 $document.head >。

If you dont want to do that, I would recommend that you change your service into a directive seeing as how injecting a script element, is manipulating the DOM. That way you would kill two birds with one stone, as you would need to inject $compile to test your directive (which would enable you to $compile a custom head element to boot). But this is slightly "over the top" for now.

实现:

if (!angular.element('#' + id).length) {
  var link = StylesheetFactory.Create(id, uri);

    link.onload = deferred.resolve;

    $document.head.append(link);

    return deferred.promise;
  }
}

之前:

/**
 * Sorry, this was previously $location which was just 
 * such a silly mistake.
 */
var $timeout; 

beforeEach(function () {
  inject(function ($injector) {
    $timeout = $injector.get('$timeout');
  });
});

它:

it('attaches the stylesheet to $document.head', function () {
  styleSheetInjectorService.inject('someId', '/path/to/some/stylesheet');
  $timeout.flush(); // flush promises
  expect(angular.element($document.head).lastChild[0].nodeName).to.eq('LINK');
});

按照这些思路应该可以让您启动并运行。请记住，我编写的规范使用 chai#expect风格断言，以及 mocha测试框架。如果您打算复制粘贴，请编辑语法以适合 Jasmine。