How do you "nest" or "group" Test::Unit tests?

RSpec has:

describe "the user" do
  before(:each) do
    @user = Factory :user
  end

  it "should have access" do
    @user.should ...
  end
end

How would you group tests like that with Test::Unit? For example, in my controller test, I want to test the controller when a user is signed in and when nobody is signed in.

You can achieve something similar through classes. Probably someone will say this is horrible but it does allow you to separate tests within one file:

class MySuperTest < ActiveSupport::TestCase
  test "something general" do
    assert true
  end

  class MyMethodTests < ActiveSupport::TestCase

    setup do
      @variable = something
    end

    test "my method" do
      assert object.my_method
    end
  end
end

Test::Unit, to my knowledge, does not support test contexts. However, the gem contest adds support for context blocks.