Add ab_test_chosen? helper and chosen? method on experiment

lib/vanity/adapters/abstract_adapter.rb

@@ -110,6 +110,11 @@ def ab_add_participant(experiment, alternative, identity)
         fail "Not implemented"
       end
 
+      # Indicates which alternative has been picked for this participant. See #ab_add_participant.
+      def ab_chosen(experiment, identity)
+        false # TODO: default to false for now; should add to each adapter
+      end
+
       # Records a conversion in this experiment for the given alternative.
       # Associates a value with the conversion (default to 1). If implicit is
       # true, add particpant if not already recorded for this experiment. If

lib/vanity/adapters/active_record_adapter.rb

@@ -220,6 +220,12 @@ def ab_add_participant(experiment, alternative, identity)
         VanityParticipant.retrieve(experiment, identity, true, :seen => alternative)
       end
 
+      # Indicates which alternative has been picked for this participant. See #ab_add_participant.
+      def ab_chosen(experiment, identity)
+        participant = VanityParticipant.retrieve(experiment, identity, false)
+        participant && participant.seen
+      end
+
       # Records a conversion in this experiment for the given alternative.
       # Associates a value with the conversion (default to 1). If implicit is
       # true, add particpant if not already recorded for this experiment. If

lib/vanity/experiment/ab_test.rb

@@ -279,6 +279,18 @@ def showing?(alternative)
         end
       end
 
+      # True if this experiment has been selected for the current id (see #chooses).
+      def chosen?
+        # True if experiment is active and a value has been chosen for current identity
+        !!if @playground.collecting? # return a boolean value
+          active? && (connection.ab_showing(@id, identity()) ||
+                      connection.ab_chosen(@id, identity()))
+                  # TODO: implement ab_chosen on all vanity adapters!!
+        else
+          @showing && @showing[identity()]
+        end
+      end
+
 
       # -- Reporting --
 

lib/vanity/helpers.rb

@@ -50,6 +50,11 @@ def ab_test(name, &block)
       end
     end
 
+    # Check whether the specified experiment has had a value chosen yet
+    def ab_test_chosen?(id)
+      Vanity.playground.experiment(id).chosen?
+    end
+
     # Tracks an action associated with a metric.
     #
     # @example