如何测试在AngularJS中调用的debug.error（）函数？

我有以下AngularJS代码：

(function() {
    "use strict";

    /**
     * @ngdoc directive
     * @name beckon.flint.pageHeader:pageHeader
     * @scope
     * @section pageLayout
     *
     * @restrict E
     *
     * @description
     * A complete page header. The header transcludes additional content such as buttons into the header row.
     *
     * <h4>Source</h4>
     * <pre>
     * No controller setup needed.
     * </pre>
     *
     * <h4>Template</h4>
     * <pre>
     * <page-header header="Available Dashboards" subheader="Reports">
     *      <flat-button ng-click="createSomething()" text="Create New Something"></flat-button>
     * </page-header>
     * </pre>
     *
     * @param {string} header - The header title.
     * @param {string} subheader - The sub-header title.
     * @param {string} helpPage - Link to documentation
     */

    angular
        .module("beckon.flint.pageHeader", ["beckon.tinder.documentation.documentationLinks"])
        .directive("pageHeader", function() {
            return {
                templateUrl: "pageHeader",
                replace: true,
                transclude: true,
                scope: {
                    header: "@",
                    subheader: "@",
                    helpPage: "@",
                    backState: "@?",
                },
                restrict: "E",
                controller: function($scope, documentationLinks, svg) {
                    $scope.icon = svg.ARROW_LEFT;
                    const documentationLink = $scope.helpPage
                        ? documentationLinks.helpPages[$scope.helpPage]
                        : null;
                    if ($scope.helpPage && !documentationLink) {
                        debug.error("Invalid help-page specified:" + $scope.helpPage);
                    }

                    $scope.helpUrl = documentationLink ? documentationLink.url : null;
                    $scope.helpText = documentationLink
                        ? documentationLink.displayInfo.explanation
                        : null;
                },
                link: function($scope, $element, attrs, controller, transcludeFn) {
                    debug.log(transcludeFn);
                },
            };
        });
})();

似乎是代码中唯一未经测试的部分，我似乎无法访问它。我尝试了

spyOn（debug，“error”）

和

expect（debug.error）.tohavebeencall（）如第二个代码段所示，但该特定测试失败

有没有一种方法可以在不修改主代码的情况下测试特定的debug.error函数是否正常工作

fdescribe("pageHeader", () => {
    "use strict";

    let $scope;
    let $compile;
    let $rootScope;

    let svg;
    let documentationLinks;

    const getIsolatedScope = (element) => element.isolateScope() || element.scope();

    beforeEach(() => {
        module("beckon.flint.pageHeader");

        module(($provide) => {
            svg = jasmine.createSpy();
            documentationLinks = {
                helpPages: {
                    MyHelpPage: {
                        url: "dummypage.com",
                        displayInfo: {
                            explanation: "A dummy page",
                        },
                    },
                },
            };

            $provide.value("svg", svg);
            $provide.value("documentationLinks", documentationLinks);
        });

        inject((_$rootScope_, _$compile_) => {
            $compile = _$compile_;
            $rootScope = _$rootScope_;
            $scope = $rootScope.$new(true);
        });
    });

    it("should initialize correctly", () => {
        // Arrange
        const element = angular.element(
            "<page-header header='My header' subheader='My sub header' backState='My BackState'>Here goes the template</page-header>"
        );

        // Act
        $compile(element)($scope);
        $scope.$digest();
        const isolatedScope = getIsolatedScope(element);
        isolatedScope.helpPage = {};
        spyOn(debug, "error");

        // Assert
        expect(isolatedScope.helpUrl).toBe(null);
        expect(isolatedScope.helpText).toBe(null);
        expect(debug.error).toHaveBeenCalled();
    });
});


if ($scope.helpPage && !documentationLink) {
    debug.error("Invalid help-page specified:" + $scope.helpPage);
}