title: TestNG Groups wise Test Execution not Working from xml file
body: <p>Please help me to execute an test with group wise using testng xml file</p>
  
  <p>i have an class with inherit a subclass</p>
  
  <pre><code>public class testcase extends Loginclass {
  </code></pre>
  
  <p>inside this class i have an multiple Test with Groups</p>
  
  <pre><code>@Test(dataProvider = "In_credentials", groups ={"Login_cred"})
  @Test(dataProvider = "Invalid_credentials", groups ={"Login_cred"})
  </code></pre>
  
  <p>so in my XML file i have to include the Group name to execute only the above test
  my xml file is</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd"&gt;
  &lt;suite name="Suite for Login" &gt;
    &lt;test name="Login validation"&gt;
    &lt;groups&gt;
    &lt;run&gt;
    &lt;include name ="Login_cred"/&gt;
    &lt;/run&gt;
    &lt;/groups&gt;
      &lt;classes&gt;
        &lt;class name="pk.webdriver.testcase"&gt;
        &lt;/class&gt;
        &lt;/classes&gt;
    &lt;/test&gt; &lt;!-- Test --&gt;
  &lt;/suite&gt; &lt;!-- Suite --&gt;
  </code></pre>
  
  <p>During the Execution i got an NUll pointer Exception, please suggest to me how we define the xml file for that above case (we are using Page Object Design Pattern)</p>
  
  <p>thanks
  prabakar M</p>