### Question:
ViewResponseFilter implements ContainerResponseFilter { private String appendExtensionIfRequired(String viewName) { return appendExtensionIfRequired(viewName, krazoConfig.getDefaultViewFileExtension()); }  @Override void filter(ContainerRequestContext requestContext,
                       ContainerResponseContext responseContext);  }### Answer:
@Test public void testAppendExtensionIfRequired() { String actualViewName = ViewResponseFilter.appendExtensionIfRequired(viewName, defaultExtension); assertEquals(expectedViewName, actualViewName); }