Rate#for should handle invalid projects. #1920

app/models/rate.rb

@@ -26,7 +26,10 @@ class Rate < ActiveRecord::Base
   
   # API to find the Rate for a +user+ on a +project+ at a +date+
   def self.for(user, project = nil, date = Date.today.to_s)
+    # Check input since it's a "public" API
     return nil unless user.is_a?(User)
+    return nil unless project.nil? || project.is_a?(Project)
+    
     rate = self.for_user_project_and_date(user, project, date)
     
     return nil if rate.nil?