title: equivalent to rspec's let in test::unit?
body: <p>Anyone know of an equivalent in test::unit to rspec's :let and :let!?  E.g.</p>
  
  <pre><code>context "foo" do
    let(:user) { Factory(:user) }
    it "bar" do
      ...
    end
  end
  </code></pre>
  
  <p>I'd love to use this convenient pattern when writing test::unit tests.<br>
  Thanks in advance.</p>