code: @Test public void shouldFallbackToExternalResourceLocatorWhenDispatcherReturns404() throws Exception {
    victim=new DispatcherStreamLocator(){
      @Override UriLocator createExternalResourceLocator(){
        return mockUriLocator;
      }
    }
  ;
    final String location="/some/location.js";
    when(mockRequest.getRequestDispatcher(location)).thenReturn(mockDispatcher);
    Mockito.doAnswer(new Answer<Void>(){
      public Void answer(    final InvocationOnMock invocation) throws Throwable {
        return null;
      }
    }
  ).when(mockDispatcher).include(Mockito.any(HttpServletRequest.class),Mockito.any(HttpServletResponse.class));
    victim.getInputStream(mockRequest,mockResponse,location);
    verify(mockUriLocator).locate(Mockito.anyString());
  }
  