title: rspec matcher on array argument similar to hash_including
body: <p>In rspec you can test that a call to a method receives an argument that is a hash and includes certain keys, or key-value pairs. That is:</p>
  
  <pre><code>my_object.should_receive(:my_method).with(hash_including(:a =&gt; 'alpha'))
  </code></pre>
  
  <p>Is there anything available to accomplish a similar match with an array? Something that would look like?</p>
  
  <pre><code>my_object.should_receive(:my_method).with(array_including('alpha'))
  </code></pre>