Why do I get 'Unable to get property 'then' of undefined or null reference'?

I wrote an angular service:

app.factory('newService', function($http, $q) {
  return {
    getCustomer: function(id) {
      var deferred = $q.defer();
      $http.get('/api/customers?id=' + id).success(function(data) {
        deferred.resolve({
          id: 1,
          name: 'Bert'
        });
      }).error(function(err, msg) {
        deferred.reject(msg);
        $log(err);
      });
      return deferred.promise;
    }
  };
});

My test looks like this:

it('should call service', function() {
    $scope.test2();
    expect(myMock.getCustomer).toHaveBeenCalledWith(2);
});

However I am getting an error:

TypeError: Unable to get property 'then' of undefined or null reference

plunkr:http://ift.tt/1KomT9H