title: NameError: wrong constant name
body: <p>I have a <code>has_many</code> / <code>belongs_to</code> polymorphic relationship between two models, PointModifier and ManualPoints.</p>
  
  <pre><code># ManualPoints Model
  has_many :point_modifiers, as: :modifier
  
  # PointModifier Model
  belongs_to :modifier, polymorphic: true
  </code></pre>
  
  <p>I recently started seeing this error in my tests - <code>NameError: wrong constant name</code> - after adding <code>ActiveModel::Serializer</code> into my project. It does not appear to be related to <code>AMS</code>, and I've never seen this error before.</p>