title: NUnit Assertion that enum value contains a flag
body: <p>While writing some tests for our .Net (C#) libraries with NUnit, I came to following problem:
  I have an enum which has the Flags attribute, e.g.</p>
  
  <pre><code>[Flags]
  public enum Powers : int
  {
      Undefined = 0,
      Zero = 1,
      One = 2,
      Two = 4,
  }
  </code></pre>
  
  <p>Now I want to write an NUnit test for checking that </p>
  
  <pre><code>Powers aValue = Powers.One | Powers.Two 
  </code></pre>
  
  <p>contains Powers.Two. Currently, I use </p>
  
  <pre><code>Assert.That((aValue &amp; Powers.Two) == Powers.Two), "something went wrong")
  </code></pre>
  
  <p>But isn't there a more elegant way to do that?
  Thanks for your hints.</p>