title: Rails - ArgumentError in using ActiveRecord::Enum
body: <p>I have created a model <code>Tester</code> with integer column <code>tester_type</code> and declared enum variable in the model. </p>
  
  <pre><code>class Tester &lt; ApplicationRecord
    enum tester_type: { junior: 0, senior: 1, group: 2 }
  end
  </code></pre>
  
  <p>I am getting below error while trying to create / initialize an object for that model:</p>
  
  <blockquote>
    <p>ArgumentError: You tried to define an enum named "tester_type" on the model "Tester", but this will generate a class method "group", which is already defined by Active Record.</p>
  </blockquote>
  
  <p>So, I tried changing <code>tester_type</code> to <code>type_of_tester</code> but it throws same error:</p>
  
  <blockquote>
    <p>ArgumentError: You tried to define an enum named "type_of_tester" on the model "Tester", but this will generate a class method "group", which is already defined by Active Record.</p>
  </blockquote>
  
  <p>I have searched for the solution and I found this error was a constant <code>ENUM_CONFLICT_MESSAGE</code> in <a href="https://apidock.com/rails/ActiveRecord/Enum" rel="noreferrer">ActiveRecord::Enum</a> class but, cannot able to find the cause of this problem.</p>
  
  <p>Please help me. </p>
  
  <p>Thanks.</p>