added comments to test_invalid_type in sqlite3 adapter test and added valid_type? method to abstract_adapter.rb and removed unnecessary method from sqlite3 adapter

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -101,6 +101,10 @@ module ActiveRecord
         @visitor             = nil
       end
 
+      def valid_type?(type)
+        true
+      end
+
       class SchemaCreation
         def initialize(conn)
           @conn  = conn

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -499,10 +499,6 @@ module ActiveRecord
         rename_column_indexes(table_name, column_name, new_column_name)
       end
 
-      def valid_type?(type)
-        true
-      end
-
       protected
         def select(sql, name = nil, binds = []) #:nodoc:
           exec_query(sql, name, binds)

activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb

@@ -30,6 +30,10 @@ module ActiveRecord
         assert @conn.valid_type?(column.type)
       end
 
+      # sqlite databses should be able to support any type and not
+      # just the ones mentioned in the native_database_types. 
+      # Therefore test_invalid column should always return true 
+      # even if the type is not valid.
       def test_invalid_column
         assert @conn.valid_type?(:foobar)
       end