Adding possibility to store overridden alternative

README.mdown

@@ -162,7 +162,7 @@ If you have an experiment called `button_color` with alternatives called `red` a
 
     http://myawesomesite.com?button_color=red
 
-will always have red buttons. This won't be stored in your session or count towards to results.
+will always have red buttons. This won't be stored in your session or count towards to results, unless you set the `store_override` configuration option.
 
 ### Reset after completion
 

lib/split/configuration.rb

@@ -11,6 +11,7 @@ class Configuration
     attr_accessor :enabled
     attr_accessor :persistence
     attr_accessor :algorithm
+    attr_accessor :store_override
 
     attr_reader :experiments
 

lib/split/helper.rb

@@ -166,6 +166,7 @@ def start_trial(trial)
       experiment = trial.experiment
       if override_present?(experiment.name)
         ret = override_alternative(experiment.name)
+        ab_user[experiment.key] = ret if Split.configuration.store_override
       elsif ! experiment.winner.nil?
         ret = experiment.winner.name
       else

spec/configuration_spec.rb

@@ -26,6 +26,10 @@
     @config.disabled?.should be_true
   end
 
+  it "should not store the overridden test group per default" do
+    @config.store_override.should be_false
+  end
+
   it "should provide a default pattern for robots" do
     %w[Baidu Gigabot Googlebot libwww-perl lwp-trivial msnbot SiteUptime Slurp WordPress ZIBB ZyBorg YandexBot AdsBot-Google Wget curl bitlybot facebookexternalhit spider].each do |robot|
       @config.robot_regex.should =~ robot

spec/helper_spec.rb

@@ -96,6 +96,22 @@
       alternative.should eql('red')
     end
 
+    it "should not store the via params forced alternative" do
+      @params = {'link_color' => 'blue'}
+      ab_user.should_not_receive(:[]=)
+      ab_test('link_color', 'blue', 'red')
+    end
+
+    context "when store_override is set" do
+      before { Split.configuration.store_override = true }
+
+      it "should store the forced alternative" do
+        @params = {'link_color' => 'blue'}
+        ab_user.should_receive(:[]=).with('link_color', 'blue')
+        ab_test('link_color', 'blue', 'red')
+      end
+    end
+
     it "should allow passing a block" do
       alt = ab_test('link_color', 'blue', 'red')
       ret = ab_test('link_color', 'blue', 'red') { |alternative| "shared/#{alternative}" }