title: How to disable Rails test parallelization *just* for system tests?
body: <p>I'm finding that the default test parallelization makes chromedriver tests highly unreliable. But I'd like to keep other tests parallel.</p>
  
  <p>I've tried this in <code>application_system_test_case.rb</code>:</p>
  
  <pre class="lang-rb prettyprint-override"><code>class ApplicationSystemTestCase &lt; ActionDispatch::SystemTestCase
    parallelize(workers: 1)
    # ...
  end
  </code></pre>
  
  <p>...but it doesn't seem to override the default.</p>
  
  <p>I'm currently using:</p>
  
  <pre><code>PARALLEL_WORKERS=1 rails test:system
  </code></pre>
  
  <p>...but I'm looking for a way to hardcode this into the project in such a way that someone else doesn't have to "just know" to always set that env var for system tests.</p>