How to run a single shoulda context test in ruby Test::Unit framework

I can typically test a regular Test::Unit method using the following commandline syntax for a method "delete_user_test":

ruby functional/user_controller_test.rb -n delete_user_test

Now when I'm using the shoulda plugin with Test::Unit I try to use the same technique as follows:

... 
context "Deleting a User" do
  should "remove user from user table" do
    ...
  end
end

Then I try to run the single test as follows:

ruby functional/user_controller_test.rb -n "test: Deleting a User should remove user from user table"

This doesn't work. Does anyone know how I can run a single context tests using shoulda and Test::Unit. I have a couple of different test in one test file and I want to only run the one using TDD without having to wait for all tests to run.