code: /** 
   * Should throw  {@link NullPointerException} when provided requestHandler's collection is null.
   */
  @Test(expected=NullPointerException.class) public void shouldNotAcceptNullRequestHandlers() throws Throwable {
    victim.setRequestHandlerFactory(new RequestHandlerFactory(){
      public Collection<RequestHandler> create(){
        return null;
      }
    }
  );
    try {
      victim.doFilter(mockRequest,mockResponse,mockFilterChain);
    }
   catch (  final WroRuntimeException e) {
      throw e.getCause();
    }
  }
  