Nikolay Sivov (@nsivov) commented about dlls/msxml3/tests/domdoc.c:
check_ws_ignored(class_ptr->name, doc3, NULL); check_ws_preserved(class_ptr->name, doc4, NULL);
hr = IXMLDOMDocument2_put_preserveWhiteSpace(doc4, 1);
ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
hr = IXMLDOMDocument2_get_preserveWhiteSpace(doc4, &b);
ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
ok(b == VARIANT_FALSE, "expected true\n");
check_ws_ignored(class_ptr->name, doc3, NULL);
Sorry, my diff was wrong. This line should be using `doc4`. And once you do that both check_ws_ignored() and check_ws_preserved() fail. So setting it to invalid value in terms of VARIANT_BOOL produces third result.