TypeError: this.i18n is not a function
    at UsersCtrl.$onInit (test-context.js:35081:41)
    at Object.<anonymous> (test-context.js:35031:31)

class UsersCtrl {
    constructor($filter) {
        this.i18n = $filter('i18n');
        this.users = [];
    }
   //Life cycle Hooks: Initialization
   $onInit() {
        this.users = [
            {name: this.i18n('USERS')}
        ];
      }
}
UsersCtrl.$inject = ['$filter'];

angular.module('app', []).controller('UsersCtrl',UsersCtrl);

export default UsersCtrl;

Import UsersCtrl from './users-controller.js';

     describe("given a new User Page", () => {
        var UserController;
        beforeEach(() => {
          angular.mock.module('app');
        });

    describe("when initialising  has completed", () => {
      beforeEach(() => {
         inject(($rootScope, $controller, $filter) => {
             const scope = $rootScope.$new();
             const filter = $filter
             UserController = $controller("UsersCtrl", { $scope: scope, $filter: filter});
          });
       });
    it("then users array for tab content should be empty initially",() => {
        const expectedActive = [];
        expect(UserController.users).toEqual(expectedActive);
     });
    });
   });