title: Referring test groups in testng.xml
body: <p>Let's say I've annotated my test class with a test group in TestNG:</p>
  
  <pre><code>@Test(group='smoke-tests')
  public class CheckEnvironmentTest {
  ...
  }
  </code></pre>
  
  <p>Is there a way to refer to this group in testng.xml? Something like this (if it was implemented):</p>
  
  <pre><code>&lt;suite name="Suite1" verbose="1" &gt;
    &lt;test name="Sequential" parallel="false" &gt;
      &lt;test-group ref="smoke-tests" /&gt;
    &lt;/test&gt;
  
    &lt;test name="ParallelGroup" parallel="classes"  &gt;
      &lt;test-group ref="regular-tests" /&gt;
    &lt;/test&gt;
  &lt;/suite&gt;
  </code></pre>