MimeContainer mimeContainer = mock(MimeContainer.class);
Resource logo = new ClassPathResource("spring-ws.png", getClass());
DataHandler dataHandler = new DataHandler(new FileDataSource(logo.getFile()));
given(mimeContainer.convertToXopPackage()).willReturn(true);
byte[] bytes = FileCopyUtils.copyToByteArray(logo.getInputStream());
BinaryObject object = new BinaryObject(bytes, dataHandler);
StringWriter writer = new StringWriter();
marshaller.marshal(object, new StreamResult(writer), mimeContainer);
assertTrue("No XML written", writer.toString().length() > 0);