@Test
public void resolveViewNameWithAcceptHeader() throws Exception {
request.addHeader("Accept", "application/vnd.ms-excel");
Map<String, MediaType> mapping = Collections.singletonMap("xls", MediaType.valueOf("application/vnd.ms-excel"));
MappingMediaTypeFileExtensionResolver extensionsResolver = new MappingMediaTypeFileExtensionResolver(mapping);
ContentNegotiationManager manager = new ContentNegotiationManager(new HeaderContentNegotiationStrategy());
manager.addFileExtensionResolvers(extensionsResolver);
viewResolver.setContentNegotiationManager(manager);
ViewResolver viewResolverMock = mock(ViewResolver.class);