* fixed a small bug with ruby 1.9.2 and #<=>

* this method is implemented for every object, so another check is
  needed

lib/polecat/storage/hash_storage.rb

@@ -46,7 +46,9 @@ module Polecat
       end
 
       def check_key key
-        raise ArgumentError, 'key does not support #<=>' unless key.respond_to?(:<=>)
+        unless key.respond_to?(:<=>) && key.respond_to?(:<=)
+          raise ArgumentError, 'key does not support #<=>' 
+        end
       end
       private :check_key
     end

spec/storage/hash_storage/add_spec.rb

@@ -17,7 +17,6 @@ describe "HashStorage#add" do
   end
 
   it "raises an error when the attribute does not support #<=>" do
-    s.add('foo', 'bar')
-    lambda { s.add(:foo, 'baz') }.should raise_error(ArgumentError)
+    lambda { s.add(nil, 'baz') }.should raise_error(ArgumentError)
   end
 end

spec/storage/hash_storage/delete_spec.rb

@@ -22,6 +22,6 @@ describe "HashStorage#delete" do
   end
 
   it "raises an error when the argument does not support #<=>" do
-    lambda { s.delete(:foo) }.should raise_error(ArgumentError)
+    lambda { s.delete(nil) }.should raise_error(ArgumentError)
   end
 end

spec/storage/hash_storage/find_spec.rb

@@ -19,6 +19,6 @@ describe "HashStorage#find" do
   end
 
   it "raises an error when the type does not know #<=>" do
-    lambda { s.find(:foo) }.should raise_error(ArgumentError)
+    lambda { s.find(nil) }.should raise_error(ArgumentError)
   end
 end