Makes #transaction method available on require 'dm-transactions'

If dm-transactions is required explicitly, assume
that an adapter with builtin transaction support
will be used eventually.

[#1232 state:resolved]

lib/dm-transactions.rb

@@ -344,13 +344,6 @@ def rollback_and_close_adapter(adapter)
     module Adapter
       extend Chainable
 
-      # @api private
-      def self.included(base)
-        [ :Repository, :Model, :Resource ].each do |name|
-          DataMapper.const_get(name).send(:include, Transaction.const_get(name))
-        end
-      end
-
       # Produces a fresh transaction primitive for this Adapter
       #
       # Used by Transaction to perform its various tasks.
@@ -487,6 +480,11 @@ def transaction
         model.transaction { |*block_args| yield(*block_args) }
       end
     end # module Resource
+
+    [ :Repository, :Model, :Resource ].each do |name|
+      DataMapper.const_get(name).send(:include, Transaction.const_get(name))
+    end
+
   end # class Transaction
 
   module Adapters

spec/dm-transactions_spec.rb

@@ -67,6 +67,20 @@ class ::Default
     @paragraph_model = Blog::Paragraph
   end
 
+  describe "require 'dm-transactions" do
+
+    it 'should not perform adapter setup' do
+      lambda { DataMapper.repository.adapter }.should raise_error(DataMapper::RepositoryNotSetupError)
+    end
+
+    %w[Repository Model Resource].each do |name|
+      it "should make #transaction available on DataMapper::#{name}" do
+        DataMapper.const_get(name).instance_methods.include?('transaction').should be_true
+      end
+    end
+
+  end
+
   supported_by :postgres, :mysql, :sqlite, :oracle, :sqlserver do
     before :all do
       user = @user_model.create(:name => 'dbussink', :age => 25, :description => 'Test')