Unit testing $rootScope.$$phase and $rootScope.$digest()

Question

My site has

$rootScope.$broadcast('task1-completed', service.options.language);

which then calls

$rootScope.$on('task1-completed', function() {
    if (!$rootScope.$$phase) {
        $rootScope.$digest();
    }
});

The unit tests work fine for the $broadcast and $on but how do I unit test the inner function? Aka make $rootScope.$$phase false so that $digest() gets called...

I have tried to mock the entire $rootScope object but was unable to get anything working that way. This is more for code coverage purposes as the unit tests all run fine. Any help is appreciated! Thanks in advance!

What is emitting an Angular event without being in a `$digest`? Are you sure that `$rootScope.$digest()` *ever* gets called in your production code? — Davin Tryon, Nov 18 '14 at 16:43
@DavinTryon I am not 100% sure that this particular line is ever called in prod, but redundancy never hurt anyone, right? — Timothy, Nov 18 '14 at 16:49

score 0 · Accepted Answer · answered Nov 18 '14 at 17:01

I was able to solve this by just changing the $on to..

$scope.onUpdate = function() {
    if (!$rootScope.$$phase) {
        $rootScope.$digest();
    }
};

$rootScope.$on('task1-completed', function() {
    $scope.onUpdate();
});

This way I can unit test the if statement, without the actual code that calls it, which makes $$phase false and ensures $digest() is called.

score 0 · Answer 2 · answered May 17 '17 at 20:06

Properties that are prefixed with $$ in Angular are considered private members and not dependable; they are implementation details that could change at any time.

From the docs: https://docs.angularjs.org/api

AngularJS Prefixes $ and $$: To prevent accidental name collisions with your code, AngularJS prefixes names of public objects with $ and names of private objects with $$...

A safe and acceptable way to accomplish this is with $scope.$evalAsync().

Docs on $evalAsync

It is a good idea, generally, that it is executed not inside your listening directive where you have it, but instead in originating code of the event so that it does not need to be duplicated everywhere that a listener exists.

$rootScope.$evalAsync(() => {
    $rootScope.$broadcast('task1-completed', service.options.language);
})

Unit testing $rootScope.$$phase and $rootScope.$digest()

2 Answers2