title: Is there a way to share assertions among test classes without inheritance in NUnit?
body: <p>In MSpec there is a neat feature that allows you share assertions between multiple tests. They're called <a href="http://lostechies.com/jamesgregory/2010/01/18/behaviours-in-mspec/" rel="noreferrer">"behaviors"</a></p>
  
  <blockquote>
    <p>Behaviours define reusable specs that encapsulate a particular set of,
    you guessed it, behaviours; you’re then able to include these specs in
    any context that exhibits a particular behaviour. </p>
  </blockquote>
  
  <p>You define them as a class with assertions (<code>It</code> fields)</p>
  
  <pre><code>public class VehicleThatHasBeenStartedBehaviors
  {
      protected static IVehicle vehicle;
      It should_have_a_running_engine = () =&gt; vehicle.IsEngineRunning.ShouldBeTrue();
      It should_be_idling = () =&gt; vehicle.RevCount.ShouldBeBetween(0, 1000);
  }
  </code></pre>
  
  <p>and include them in your test class like</p>
  
  <pre><code>public class when_starting_a_car
  {
      Behaves_like&lt;VehicleThatHasBeenStartedBehaviors&gt; a_started_vehicle;
  }
  </code></pre>
  
  <p>How can I accomplish the same with NUnit?</p>