Merge pull request #102 from zendesk/ben/expose_formula

allow threshold argument to `passes_threshold?` to enable re-use in subclasses

lib/arturo/feature.rb

@@ -55,7 +55,7 @@ def enabled_for?(feature_recipient)
       return false if feature_recipient.nil?
       return false if blacklisted?(feature_recipient)
       return true if  whitelisted?(feature_recipient)
-      passes_threshold?(feature_recipient)
+      passes_threshold?(feature_recipient, deployment_percentage || 0)
     end
 
     def name
@@ -79,10 +79,8 @@ def self.last_updated_at
       maximum(:updated_at)
     end
 
-    protected
-
-    def passes_threshold?(feature_recipient)
-      threshold = self.deployment_percentage || 0
+    # made public so as to allow for thresholds stored outside of the model
+    def passes_threshold?(feature_recipient, threshold)
       return true if threshold == 100
       return false if threshold == 0 || !feature_recipient.id
       (((feature_recipient.id + (self.id || 1) + 17) * 13) % 100) < threshold