test collector for ivar assignment

lib/melon/type_collector.rb

@@ -12,10 +12,18 @@ module Melon
     end
 
     def on_ivar(statement)
+      add_ivar(statement)
+    end
+
+    def on_ivasgn( statement )
+      add_ivar(statement)
+    end
+
+    def add_ivar(statement)
       var = statement.children[0].to_s[1..-1].to_sym
       @ivars[var] = :Object #guess, can maybe guess better
     end
-
+    
     def handler_missing(node)
       node.children.each do |kid |
         process(kid) if kid.is_a?(AST::Node)