title: Handling Exceptions in Python Behave Testing framework
body: <p>I've been thinking about switching from nose to behave for testing (mocha/chai etc have spoiled me). So far so good, but I can't seem to figure out any way of testing for exceptions besides:</p>
  
  <pre><code>@then("It throws a KeyError exception")
  def step_impl(context):
  try:
      konfigure.load_env_mapping("baz", context.configs)
  except KeyError, e:
      assert (e.message == "No baz configuration found") 
  </code></pre>
  
  <p>With nose I can annotate a test with </p>
  
  <pre><code>@raises(KeyError)
  </code></pre>
  
  <p>I can't find anything like this in behave (not in the source, not in the examples, not here). It sure would be grand to be able to specify exceptions that might be thrown in the scenario outlines.</p>
  
  <p>Anyone been down this path? </p>