title: How to change behaviour of stubs?
body: <p>Can I change the behaviour of a stub during runtime? Something like:</p>
  
  <pre><code>    public interface IFoo { string GetBar(); }
      [TestMethod]
      public void TestRhino()
      {
          var fi = MockRepository.GenerateStub&lt;IFoo&gt;();
          fi.Stub(x =&gt; x.GetBar()).Return("A");
          Assert.AreEqual("A", fi.GetBar());
          fi.Stub(x =&gt; x.GetBar()).Return("B");
          Assert.AreEqual("B", fi.GetBar());    // Currently fails here
      }
  </code></pre>
  
  <p>My code example still fails in the given line, <code>fi.GetBar()</code> still returns <code>"A"</code>.</p>
  
  <p>Or is there another trick to model stubs whose behaviour changes over time? I'd rather not resort to using <code>fi.Stub(...).Do(...)</code>.</p>
  
  <p>Ah, probably I just need hardcopy of the fine manual for somebody to hit me over the head with it. It looks like it should really be obvious, but I can't find it.</p>