This test can't work when the in-memory representation is UTF-16, as we can't convert surrogates to anything else in this case. This fixes the unit tests broken since r76622, see #16298. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78022 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775