Move datamapper specs into backends directory

Rakefile

@@ -24,6 +24,10 @@ Jeweler::Tasks.new do |s|
   s.add_development_dependency "rspec"
   s.add_development_dependency "sqlite3-ruby"
   s.add_development_dependency "mongo_mapper"
+  s.add_development_dependency "dm-core"
+  s.add_development_dependency "dm-observer"
+  s.add_development_dependency "dm-aggregates"
+  s.add_development_dependency "do_sqlite3"
 end
 
 require 'spec/rake/spectask'

spec/datamapper_job_spec.rb → spec/backend/datamapper_job_spec.rb

@@ -1,10 +1,7 @@
 require 'spec_helper'
-
+require 'backend/shared_backend_spec'
 require 'delayed/backend/data_mapper'
 
-DataMapper.logger = ActiveRecord::Base.logger
-DataMapper.setup(:default, "sqlite3::memory:")
-
 describe Delayed::Backend::DataMapper::Job do
   before(:all) do
     @backend = Delayed::Backend::DataMapper::Job

spec/setup/data_mapper.rb

@@ -0,0 +1,4 @@
+require 'dm-core'
+
+DataMapper.logger = ActiveRecord::Base.logger
+DataMapper.setup(:default, "sqlite3::memory:")