title: Cannot subclass final class class with powermock
body: <p>I have a "final" class, in which I need to test private methods, 
  tried the following way for the failure case to get (Exception) but getting error</p>
  
  <blockquote>
    <p>[junit] Caused by: IllegalArgumentException: Cannot subclass
    final class class</p>
  </blockquote>
  
  <p>How to resolve this error, can anyone please suggest</p>
  
  <pre><code>//final class
  public final Class Test {
  
    //private constructor
    private Test(Events event) {
       //initialization
    }
  
    private JSONObject getReg() {
      return new JSONObject;
    }
  
    private State Updation(String macAddr) {
      try {
        return update(getReg(), PATH, macAddr);
      } catch (Exception e) {
        throw new JSONException(e);
      } 
    }
  
   }
  
  
   @PrepareForTest({Test.class})
   @RunWith(PowerMockRunner.class)
   public class TestClassTest {
  
   @Test(expected = Exception.class)
   public void UpdationInvalidTest() throws Exception {
     JSONObject jsonObj = new JSONObject();
  
     Test test = Whitebox.invokeConstructor(Test.class, event);
  
     Test testSpy = PowerMockito.spy(test);
     PowerMockito.doReturn(jsonObj).when(testSpy, "getReg");
  
     Whitebox.invokeMethod(test, "Updation", "00:00:00:00:00:00");
   }
  }
  </code></pre>