title: RSpec when to use it should respond_to
body: <p>I have two models linked together by a <code>belongs_to</code> and <code>has_many</code> relationship as shown below. </p>
  
  <pre><code>Class OtherModel &lt; ActiveRecord::Base
    belongs_to my_model
  end
  
  class MyModel &lt; ActiveRecord::Base
    has_many other_models
  end
  </code></pre>
  
  <p>I now have the respective tests to verify that they have the correct relationship shown below.</p>
  
  <pre><code>RSpec.describe MyModel, type: :model do
    it {should have_many(:other_models)}
    it {should respond_to(:other_models)}
  end
  
  RSpec.describe OtherModel, type: :model do
    it {should have_many(:my_model)}
    it {should respond_to(:my_model)}
  end
  </code></pre>
  
  <p>For this relationship, is the <code>respond_to</code> required, and if so why? What does it check for that the have_many does not already check for? If the <code>respond_to</code> is not needed in this case, when is an appropriate time to use it? From my current understanding <code>have_many</code> already verifies that the field exists, and thus obsoletes the <code>respond_to</code> check. </p>