title: Test ActiveModel::Serializer classes with Rspec
body: <p>Given the following <code>ActiveModel::Serializer</code> class:</p>
  
  <pre><code>class SampleSerializer &lt; ActiveModel::Serializer
    attributes :id, :name
  end
  </code></pre>
  
  <p>How can this be tested with <code>RSpec</code>?</p>