test_context.rb

class ActiveSupport::TestCase
  class << self
    def context(name, &block)
      _context_stack_.unshift name.gsub(/\s+/,'_')
      define_callbacks :"setup_#{_current_context_}", :"teardown_#{_current_context_}"
      class_eval(&block)
      _context_stack_.pop
    end

    def test_with_context(name, &block)
      if _current_context_
        callbacks = [:"setup_#{_current_context_}", :"teardown_#{_current_context_}"]
        test_without_context("#{_current_context_}__#{name}") do
          run_callbacks callbacks[0]
          block.bind(self).call
          run_callbacks callbacks[1]
        end
      else
        test_without_context(name, &block)
      end
    end
  
    def setup_with_context(*methods, &block)
      if _current_context_
        self.send("setup_#{_current_context_}", *methods, &block)
      else
        setup_without_context(*methods, &block)
      end
    end

    def teardown_with_context(*methods, &block)
      if _current_context_
        self.send("teardown_#{_current_context_}", *methods, &block)
      else
        teardown_without_context(*methods, &block)
      end
    end

    def _context_stack_
      @_context_stack_ ||= []
    end
  
    def _current_context_
      _context_stack_[0]
    end

    alias_method_chain :test, :context
    alias_method_chain :setup, :context
    alias_method_chain :teardown, :context
  end
end

class MyTest < ActiveSupport::TestCase
  setup :common_setup

  context "When logged in" do
    setup :login
 
    test "GET /" do
    end
  end

  context "When logged out" do
    test "GET /" do
    end
  end 
end