@Test(expected = IllegalStateException.class)
public void wizardCantGoBackIfNoPreviousSteps() throws Exception {

  DummyModel model = new DummyModel();
  ModelWizard wizard = new ModelWizard.Builder(new DummyStep(model), new DummyStep(model)).build();
  try {
    runInvokerAndGoForward(wizard);
    runInvokerAndGoBack(wizard);
    runInvokerAndGoBack(wizard);
  }
  finally {
    Disposer.dispose(wizard);
  }
}