QUnit: why can't setup expose data to tests properly?

gistfile1.js

/*
  Am I missing something here or is this really the way to go for a 
  module's setup function to expose something to the module's tests?
*/
(function() {
  var filled_by_setup;
  module('dummy module', {
    setup: function() {
      // prepare some data
      filled_by_setup = Math.random();
    }
  });
  test('something', function() {
    equal(typeof filled_by_setup, 'Number', 'is it really?');
  })
})();