Understanding Angular's `inject` with Testing

Question

Looking at an example from Mastering Web Applications in AngularJS:

angular.module('archive', [])
  .factory('notificationsArchive', function () {
     var archivedNotifications = [];
     return {
        archive:function (notification) {
            archivedNotifications.push(notification);
        },
        getArchived:function () {
            return archivedNotifications;
        }};
  });

Then, the module's test:

describe('notifications archive tests', function () {
   var notificationsArchive;

   beforeEach(module('archive'));

   beforeEach(inject(function (_notificationsArchive_) {
        notificationsArchive = _notificationsArchive_;
   }));

   it('should give access to the archived items', function () {
       var notification = {msg: 'Old message.'};

    notificationsArchive.archive(notification);

    expect(notificationsArchive.getArchived())
          .toContain(notification);
    });
});

What's going on in the second beforeEach(inject ...?

rob · Accepted Answer · 2014-05-27 17:29:54Z

2

beforeEach(inject(function (_notificationsArchive_) {
    notificationsArchive = _notificationsArchive_;
}));

That's just saying before each test, get an instance of notificationsArchive. It then assigns that instance to a variable that can be used in the actual test case. The underscores around notificationsArchive are just syntactic sugar so you don't have to come up with another name for the variable that your test users.

answered May 27, 2014 at 17:29

rob

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Dr Discobolus · Accepted Answer · 2014-05-27 17:43:11Z

2

It is injecting the notificationsArchive service into a function that assigns that service to the local variable "notificationsArchive" before each test. The underscores in the name are ignored.

https://docs.angularjs.org/api/ngMock/function/angular.mock.inject

answered May 27, 2014 at 17:43

Dr Discobolus

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