feat(DecisionListener): Adds experiment decision listener.

lib/optimizely.rb

@@ -143,12 +143,17 @@ def get_variation(experiment_key, user_id, attributes = nil)
       end
 
       variation_id = @decision_service.get_variation(experiment_key, user_id, attributes)
+      variation = @config.get_variation_from_id(experiment_key, variation_id) unless variation_id.nil?
+      variation_key = variation['key'] if variation
 
-      unless variation_id.nil?
-        variation = @config.get_variation_from_id(experiment_key, variation_id)
-        return variation['key'] if variation
-      end
-      nil
+      @notification_center.send_notifications(
+        NotificationCenter::NOTIFICATION_TYPES[:DECISION],
+        Helpers::Constants::DECISION_INFO_TYPES['EXPERIMENT'], user_id, (attributes || {}),
+        experiment_key: experiment_key,
+        variation_key: variation_key
+      )
+
+      variation_key
     end
 
     # Force a user into a variation for a given experiment.

lib/optimizely/helpers/constants.rb

@@ -352,6 +352,12 @@ module Constants
         'UNKNOWN_MATCH_TYPE' => 'Audience condition %s uses an unknown match type. You may need ' \
         'to upgrade to a newer release of the Optimizely SDK.'
       }.freeze
+
+      DECISION_INFO_TYPES = {
+        'EXPERIMENT' => 'experiment',
+        'FEATURE' => 'feature',
+        'FEATURE_VARIABLE' => 'feature_variable'
+      }.freeze
     end
   end
 end

lib/optimizely/notification_center.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 #
-#    Copyright 2017-2018, Optimizely and contributors
+#    Copyright 2017-2019, Optimizely and contributors
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ class NotificationCenter
 
     NOTIFICATION_TYPES = {
       ACTIVATE: 'ACTIVATE: experiment, user_id, attributes, variation, event',
+      DECISION: 'DECISION: type, user_id, attributes, decision_info',
       TRACK: 'TRACK: event_key, user_id, attributes, event_tags, event'
     }.freeze
 

spec/project_spec.rb

@@ -592,11 +592,17 @@ class InvalidErrorHandler; end
         .with('test_experiment')
         .and_return([])
       experiment = project_instance.config.get_experiment_from_key('test_experiment')
+
+      # Decision listener
+      expect(project_instance.notification_center).to receive(:send_notifications).ordered
+
+      # Activate listener
       expect(project_instance.notification_center).to receive(:send_notifications).with(
         Optimizely::NotificationCenter::NOTIFICATION_TYPES[:ACTIVATE],
         experiment, 'test_user', nil, variation_to_return,
         instance_of(Optimizely::Event)
-      )
+      ).ordered
+
       project_instance.activate('test_experiment', 'test_user')
 
       expect(spy_logger).to have_received(:log).once.with(Logger::INFO, include('Dispatching impression event to' \
@@ -649,6 +655,36 @@ class InvalidErrorHandler; end
       invalid_project = Optimizely::Project.new('invalid')
       invalid_project.activate('test_exp', 'test_user')
     end
+
+    describe '.decision listener' do
+      it 'should call decision listener when user not in experiment' do
+        expect(project_instance.notification_center).to receive(:send_notifications).with(
+          Optimizely::NotificationCenter::NOTIFICATION_TYPES[:DECISION],
+          'experiment', 'test_user', {},
+          experiment_key: 'test_experiment_with_audience', variation_key: nil
+        )
+
+        project_instance.activate('test_experiment_with_audience', 'test_user')
+      end
+
+      it 'should call decision listener when user in experiment' do
+        variation_to_return = project_instance.config.get_variation_from_id('test_experiment', '111128')
+        allow(project_instance.decision_service.bucketer).to receive(:bucket).and_return(variation_to_return)
+        expect(project_instance.event_dispatcher).to receive(:dispatch_event).with(instance_of(Optimizely::Event))
+
+        # Decision listener
+        expect(project_instance.notification_center).to receive(:send_notifications).with(
+          Optimizely::NotificationCenter::NOTIFICATION_TYPES[:DECISION],
+          'experiment', 'test_user', {},
+          experiment_key: 'test_experiment', variation_key: 'control'
+        ).ordered
+
+        # Activate listener
+        expect(project_instance.notification_center).to receive(:send_notifications).ordered
+
+        project_instance.activate('test_experiment', 'test_user')
+      end
+    end
   end
 
   describe '#track' do
@@ -1066,6 +1102,28 @@ class InvalidErrorHandler; end
       invalid_project = Optimizely::Project.new('invalid')
       invalid_project.get_variation('test_exp', 'test_user')
     end
+
+    describe '.decision listener' do
+      it 'should call decision listener when user in experiment' do
+        expect(project_instance.notification_center).to receive(:send_notifications).with(
+          Optimizely::NotificationCenter::NOTIFICATION_TYPES[:DECISION],
+          'experiment', 'test_user', {'browser_type' => 'firefox'},
+          experiment_key: 'test_experiment_with_audience', variation_key: 'control_with_audience'
+        )
+
+        project_instance.get_variation('test_experiment_with_audience', 'test_user', 'browser_type' => 'firefox')
+      end
+
+      it 'should call decision listener when user not in experiment' do
+        expect(project_instance.notification_center).to receive(:send_notifications).with(
+          Optimizely::NotificationCenter::NOTIFICATION_TYPES[:DECISION],
+          'experiment', 'test_user', {'browser_type' => 'chrome'},
+          experiment_key: 'test_experiment_with_audience', variation_key: nil
+        )
+
+        project_instance.get_variation('test_experiment_with_audience', 'test_user', 'browser_type' => 'chrome')
+      end
+    end
   end
 
   describe '#is_feature_enabled' do