How to simulate time passing in angularjs test?

Question

I am trying to pass a simulate time passing in an angularjs jasmine test.

My directive that I am testing simply displays the current time and updates every second:

return {
  restrict: 'A',
  scope: {
    format: '@'
  },
  link: function (scope, element, attrs) {

    var timeout;

    function updateElement() {
      if (scope.format) {
        element.text($filter('date')(new Date(), scope.format));
      }
    }

    function updateTime() {
      updateElement();
      timeout = $timeout(function () {
        updateTime();
      }, 1000);
    }

    element.bind('$destroy', function () {
      $timeout.cancel(timeout);
    });

    updateTime();
  }
};

In my test I need to simulate time passing. I tried with $timeout and $timeout.flush but I think I am using it wrong:

it('should update every second', function () {
  $scope.$digest();
  console.log('before: ' + element.text());
  var before = element.text();

  // Wait for a couple seconds...
  $timeout(function () {
    $scope.$digest();
    console.log('after: ' + element.text());
    expect(element.text()).not.toEqual(before);
  }, 5000);

  $timeout.flush(5000);
});

Should I use $timeout to simulate time passing by or is their another method to do so?

Plunker: http://plnkr.co/edit/0V4AFGXqSfc9iLCuZbvn?p=preview

Simeon Cheeseman · Accepted Answer · 2014-07-31 04:36:20Z

1

If you wrap the $scope.$digest() inside a setTimeout it should work. Like so:

setTimeout(function(){
  $timeout.flush();
  console.log('after: ' + element.text());
  expect(element.text()).not.toEqual(before);
}, 5000);

$timeout.flush() works in tests by just calling all the callbacks registered by $timeout regardless of their time value so you have to do the timeout outside of angular in this case. As you're only looking for a change every second your code would be calling updateElement() twice within one second.

edited Jul 31, 2014 at 4:36

answered Jul 30, 2014 at 23:48

Simeon Cheeseman

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