title: rails test:case integration how to specify format
body: <p>I've this </p>
  
  <pre><code>post(my_path, params: {param: :one}, format: :js)
  </code></pre>
  
  <p>However I receive this error </p>
  
  <pre><code>ArgumentError: unknown keyword: format
  </code></pre>
  
  <p>What is the right way to do this? </p>