angularjs - error in angular.mock.inject when testing service -

i want make test of service in angularjs there problem injector.

here service:

var projectapp = angular.module("projectapp", []);  projectapp.service("worktimeservice", function(){      this.workhours = function(workhours){         return workhours;     } } 

here test:

describe("unit: testing services", function(){     var worktimeservice;      beforeeach(function(){         module("projectapp");     });     beforeeach(inject(function(_worktimeservice_){         worktimeservice = _worktimeservice_;     }));      it('should have funtion', function(){         expect(angular.isfunction(worktimeservice.workhours)).tobe(true);     }); }); 

i have made in tutorials jasmine says worktimeservice undefined.