Getting nullpointer exception for getResourceResolver() while writing Junit testcases

Hi,

I am trying to write JUnit testcases for one component using mockito and powermock frameworks.In that I am geeting nullpointer exception for getResourceResolver() method.

My actual code is as below

Session session =

null;

session = getResourceResolver().adaptTo(

Session.

class);

Node root = session.getRootNode();

I created JUnit test class as below

@Mock

ResourceResolver resourceResolver;

@Mock

Session session;

@Mock

SlingHttpServletRequest request;

when(request.getResourceResolver()).thenReturn(resourceResolver);

when(resourceResolver.adaptTo(javax.jcr.Session.class)).thenReturn((javax.jcr.Session)session);

Can any one help me on this issue ?How to mock those values?