JS模拟承诺在http调用

Question

我正在针对我的js控制器编写单元测试，该控制器通过资源启动http调用 - ＆gt;服务。我需要模拟http调用并进入response.then initialCompetitions方法（从未发生过）

controller.js

class Controller {
    constructor(
        this.competitions = [];
    )

    $onInit() {
        this.initialCompetitions();
    }

    initialCompetitions = function() {
        let response = this.service.allCompetitions();
        var vm = this;
        response.then(function(value) {
            vm.competitions = value.data;
        });
    };
}
export default Controller;

service.js

class Service {
    allCompetitions = function () {
        return this.competitionResource.all();
    };
}
export default Service;

competitionResource.js

class CompetitionResource {
    constructor($http, $q) {
        this.$http = $http;
        this.apiUrlAll = 'path to api';
        this.$q = $q;
    }

    all = function() {
        var defer = this.$q.defer();

        this.$http({
            url: this.apiUrlAll,
            method: 'GET'
        })
        .then(function(response) {
            defer.resolve(response);
        },
        function(response) {
            defer.reject(response);
        });

        return defer.promise;
    }
}
export default CompetitionResource;

单元测试规范文件：

describe('unit test', () => {
    let $rootScope, $location, $scope, $compile, controller, $q, mockData, service;

    mockData = {
        // data to mock
    };

    beforeEach(inject(($injector) => {
        $rootScope = $injector.get('$rootScope');
        $scope = $rootScope.$new();
        $location = $injector.get('$location');
        $compile = $injector.get('$compile');
        $q = $injector.get('$q');
    }));

    beforeEach(() => {
        service = {
            allCompetitions: function() {
                var deferred = $q.defer();
                deferred.resolve(mockCompetitionsData);
                return deferred.promise;
            }
        };
        controller = new Controller();
    });

    describe('initialCompetitions()', () => {

    it('should populate competitions', () => {

        expect(controller.competitions).to.be.empty;
        controller.initialCompetitions();
        expect(controller.competitions).to.not.be.empty; // fails because competitions are still empty

    });

});

});

expect(controller.competitions).to.not.be.empty;失败，因为competitions仍然是一个空数组[]

我怀疑我需要以某种不同的方式嘲笑承诺，但无法弄清楚如何。