feat(Core): onStart callback

Author: Kamil Kisiela

src/modules/core.js

@@ -45,6 +45,12 @@ angular.module(name, [
       fn = this.$bindToContext($Mixer.caller, fn || angular.noop);
       cb = cb ? this.$bindToContext($Mixer.caller, cb) : angular.noop;
 
+      // Additional callbacks specific for this library
+      // onStart - right after Meteor.subscribe()
+      const hooks = {
+        onStart: angular.noop
+      };
+
       if (!_.isString(subName)) {
         throw Error('argument 1 must be a string');
       }
@@ -55,6 +61,16 @@ angular.module(name, [
         throw Error('argument 3 must be a function or an object');
       }
 
+      if (_.isObject(cb)) {
+        for (const hook in hooks) {
+          if (hooks.hasOwnProperty(hook) && cb[hook]) {
+            // Don't use any of additional callbacks in Meteor.subscribe
+            hooks[hook] = cb[hook];
+            delete cb[hook];
+          }
+        }
+      }
+
       const result = {};
 
       const computation = this.autorun(() => {
@@ -66,6 +82,9 @@ angular.module(name, [
         }
 
         const subscription = Meteor.subscribe(subName, ...args, cb);
+
+        hooks.onStart();
+
         result.ready = subscription.ready.bind(subscription);
         result.subscriptionId = subscription.subscriptionId;
       });

tests/integration/core.spec.js

@@ -180,7 +180,7 @@ describe('angular-meteor.core', function() {
       it('should call subscription callbacks object using view model as context', function(done) {
         var vm = scope.viewModel({});
 
-        var next = _.after(2, done);
+        var next = _.after(3, done);
 
         spyOn(Meteor, 'subscribe').and.callFake(function(name, cbs) {
           cbs.onReady();
@@ -197,6 +197,26 @@ describe('angular-meteor.core', function() {
           onReady: function() {
             expect(this).toEqual(vm);
             next();
+          },
+
+          onStart: function() {
+            expect(this).toEqual(vm);
+            next();
+          }
+        });
+      });
+
+      it('should call onStart callback after Meteor.subscribe has been called', function(done) {
+        var vm = scope.viewModel({});
+
+        spyOn(Meteor, 'subscribe').and.callFake(function() {
+          return { ready: angular.noop };
+        });
+
+        vm.subscribe('test', angular.noop, {
+          onStart: function() {
+            expect(Meteor.subscribe).toHaveBeenCalled();
+            done();
           }
         });
       });