title: Rails 6.1.4 Deprecation warning: Rendering actions with '.'
body: <p>I'm receiving a deprecation warning when running <code>rails test</code>. That warning being below. Any help is appreciated in identifying what I'm doing incorrectly.</p>
  <p>(Edit: Side note, the render MUST break and return from the current controller call. I attempted to use <code>ApplicationController.render(...)</code> in place of the current <code>render</code> call, but that did not return from the controller call and I was receiving errors/warnings of <code>:no_content rendered</code>.)</p>
  <p>Warning:</p>
  <pre><code>DEPRECATION WARNING: Rendering actions with '.' in the name is deprecated: actions/action_success.json (called from update at /&lt;path&gt;/app/controllers/table_base_controller.rb:39)
  </code></pre>
  <p>The code throwing the warning is specifically this call to <code>render</code> within a controller:</p>
  <pre><code>render('/actions/action_success.json', locals: {
    view: action.lookup_view('default'),
    action: action,
    area: current_area,
    account: current_account
  }) 
  </code></pre>
  <p>I've tried taking off the <code>.json</code> as directed (also tried adding <code>template: &lt;path&gt;</code>, tried <code>file: &lt;path&gt;</code>), however, I receive this error in the test console:</p>
  <pre><code>Error:
  TableControllerTest#test_Admin_should_update_via_loan_table:
  ActionView::MissingTemplate: Missing template actions/action_success with {:locale=&gt;[:en], :formats=&gt;[:html], :variants=&gt;[], :handlers=&gt;[:raw, :erb, :html, :builder, :ruby, :jbuilder]}. Searched in:
    * &quot;/&lt;path&gt;/app/views&quot;
  
      app/controllers/table_base_controller.rb:39:in `update'
      app/controllers/application_controller.rb:79:in `with_account'
      test/controllers/table_controller_test.rb:14:in `block in &lt;class:TableControllerTest&gt;'
  </code></pre>
  <p>The file in question (path: <code>app/views/actions/action_success.json.jbuilder</code>):</p>
  <pre><code># frozen_string_literal: true
  
  json.status 'success'
  json.status_code 200
  json.messages action.messages
  
  if view
    json.result do
      json.partial! view.to_s, result: action.result, locals: { area: area }
    end
  else
    json.result action.result
  end
  </code></pre>