gistfile1.rb

ruby-1.9.2-p136 :001 > require 'spec/rails'
 => [] 
ruby-1.9.2-p136 :002 > Spec::Example::ExampleGroupHierarchy.new(::Spec::Rails::Example::ControllerExampleGroup)
1: Spec::Rails::Example::ControllerExampleGroup
2: Spec::Rails::Example::ControllerExampleGroup
3: Spec::Rails::Example::ControllerExampleGroup
1: Spec::Rails::Example::FunctionalExampleGroup
2: Spec::Rails::Example::FunctionalExampleGroup
3: Spec::Rails::Example::FunctionalExampleGroup
1: ActionController::TestCase
2: ActionController::TestCase
3: ActionController::TestCase
1: ActiveSupport::TestCase
2: ActiveSupport::TestCase
3: ActiveSupport::TestCase
1: Test::Unit::TestCase
2: Test::Unit::TestCase
6: Test::Unit::TestCase
4: ActiveSupport::TestCase
5: ActiveSupport::TestCase
6: ActiveSupport::TestCase
4: ActionController::TestCase
5: ActionController::TestCase
6: ActionController::TestCase
4: Spec::Rails::Example::FunctionalExampleGroup
5: Spec::Rails::Example::FunctionalExampleGroup
6: Spec::Rails::Example::FunctionalExampleGroup
4: Spec::Rails::Example::ControllerExampleGroup
5: Spec::Rails::Example::ControllerExampleGroup
6: Spec::Rails::Example::ControllerExampleGroup
 => [Test::Unit::TestCase, ActiveSupport::TestCase, ActionController::TestCase, Spec::Rails::Example::FunctionalExampleGroup, Spec::Rails::Example::ControllerExampleGroup] 
ruby-1.9.2-p136 :003 > require 'remarkable_activerecord'
 => [] 
ruby-1.9.2-p136 :004 > require 'remarkable_rails'
 => [] 
ruby-1.9.2-p136 :005 > Spec::Example::ExampleGroupHierarchy.new(::Spec::Rails::Example::ControllerExampleGroup)
1: Spec::Rails::Example::ControllerExampleGroup
2: Spec::Rails::Example::ControllerExampleGroup
3: Spec::Rails::Example::ControllerExampleGroup
4: Spec::Rails::Example::ControllerExampleGroup
SystemStackError: stack level too deep

Did you ever figure out why this error is occuring. I am running into the same situation and having some difficulty tracing the exception path.