added truncation strategy for AR. improved error messaging

features/cleaning.feature

@@ -13,3 +13,4 @@ Feature: database cleaning
   Examples:
     | ORM          | Strategy      |
     | ActiveRecord | transaction   |
+    | ActiveRecord | truncation    |

lib/database_cleaner/active_record/truncation.rb

@@ -0,0 +1,47 @@
+
+module ActiveRecord
+  module ConnectionAdapters
+    class MysqlAdapter
+      def truncate_tabe(table_name)
+        execute("TRUNCATE TABLE #{table_name};")
+      end
+    end
+
+    class SQLite3Adapter
+      def truncate_table(table_name)
+        execute("DELETE FROM #{table_name};")
+      end
+    end
+
+  end
+
+end
+
+
+module DatabaseCleaner::ActiveRecord
+  class Truncation
+
+    def start
+      # no-op
+    end
+
+
+    def clean
+      connection.disable_referential_integrity do
+        (connection.tables - %w{schema_migrations}).each do |table_name|
+          connection.truncate_table table_name
+        end
+      end
+  end
+
+  private
+
+    def connection
+      ActiveRecord::Base.connection
+    end
+
+  end
+
+end
+
+

lib/database_cleaner/configuration.rb

@@ -4,6 +4,13 @@ module DatabaseCleaner
   class NoORMDetected < StandardError;   end
   class UnknownStrategySpecified < ArgumentError;   end
 
+  module ActiveRecord
+    def self.available_strategies
+      ['truncation', 'transaction']
+    end
+
+  end
+
   class << self
     def strategy=(args)
       strategy, *strategy_args = args
@@ -37,7 +44,7 @@ module DatabaseCleaner
       require "database_cleaner/#{orm}/#{strategy}"
       orm_module.const_get(strategy.to_s.capitalize)
     rescue LoadError => e
-      raise UnknownStrategySpecified, "foo"
+      raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!  Available strategies: #{orm_module.available_strategies.join(', ')}"
     end