Not sure where to start with unit testing angular directive

I am trying to unit test the following directive. How ever I'm not sure in this case how or even what to test.

The part I am testing is the link function to my knowledge I can only test the outcome of calling watch. In the case below is there anything that I can test?

I originally wanted to make sure modalInstance was called but im not sure this is possible.

The directive: angular.module('pb.roles.directives') .directive('pbRolesModal', ['$modal', 'pbRoles', function ($modal, pbRoles) {

        return {
            restrict: 'A',
            link: function (scope, element, attrs) {
                scope.$watch(attrs.pbRolesModal, function (entity) {
                    if (entity) {
                        element.click(function () {
                            var modalInstance = $modal.open({
                                templateUrl: '/app/roles/views/_peopleRoles.html',
                                controller: 'RolesController',
                                resolve: {
                                    entityId: function () {
                                        return entity.entityId;
                                    },
                                    enabledRoles: function () {
                                        return entity.enabledRoles || 0;
                                    }
                                }
                            });
                        });
                    }
                });
            }
        };

    }]);

My setup so far:

describe('pbRolesModal', function () {

    beforeEach(module(function ($provide) {
        $provide.constant('organizationService', function () { });
        $provide.service('activeProfile', function () { });
    }));

    beforeEach(module('pb.roles'));
    beforeEach(module('pb.roles.directives'));
    beforeEach(module('ui.router'));
    beforeEach(module('ui.bootstrap'));

    var compile, scope, element, isolate;

    var html = '<button data-pb-role-auth data-pb-granted-roles="campaign.personRoles" data-pb-keep="Admin,Manager" data-ng-disabled="!campaign" data-pb-roles-modal="campaign" data-ng-class="{ \'btn-sm\': isHeaderMin }" class="btn btn-default-alt"><span class="fa fa-users"></span></button>';


    beforeEach(inject(function ($compile, $rootScope, $q, $injector) {
        compile = $compile
        scope = $rootScope.$new();

        $httpBackend = $injector.get('$httpBackend');
        $httpBackend.whenGET('/app/roles/views/_peopleRoles.html').respond(200, '');

        element = compile(html)(scope);
        //$httpBackend.flush();
        scope.$digest();
    }));

    describe('$watch', function () {

        it('', function () {

        });

    });


});