How to solve my unit test issue in my case

I am trying to write a unit test for my codes and I need some guidance.

I have something in my file like

//inside my 'testCtrl' I have
$scope.calculateTime = function() {
    var date = new Date();
    $scope.currentYear = date.getFullYear();
}

$scope.calculateLastYear = function() {
    $scope.currentYear = $scope.currentYear - 1;
}

my test file.

describe('Controller: testCtrl', function(){
    beforeEach(module('myApp'));
    beforeEach(inject(function(_$controller_, _$rootscope_) {
        scope._$rootScope.$new();

        testCtrl = _$controller_('testCtrl', {
            $scope:scope 
        })
    })

    //for some reason, every tests I write below are passed even  
    //though it should fail

      it('should get the last year'), function() {
            expect(scope.currentYear).toBe('text here….') //<-- it should fail but   
                                                          //it passes
      };
})

I am not sure how to write the test to check the calculateLastYear function and I don't know why my expect(scope.currentYear).toBe('text here….') passed. Can anyone help me about it? Thanks a lot!