// In normal operation this is done at the DOMTransformer level.
// @todo I would rather pass a DOMProtocolMock than null, but mocks are
// currently not accessible from integration tests, and StyledDOMTester
// is not accessible from unit tests.... so move this to unit tests and
// use a DOMProtocolMock when that becomes possible.
NullRemovingDOMTransformer nullRemover = new NullRemovingDOMTransformer();
nullRemover.transform(null, dom);
String domAsString = helper.render(dom);
String expectedDOMAsString = helper.render(expectedDOM);