Make assert message in GraphicsContextDrawingTestCase more informative.

Include the paths of the files that we failed to copy.

See #16260.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76553 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/drawing/drawing.cpp

@@ -143,8 +143,11 @@ void GraphicsContextDrawingTestCase::RunIndividualDrawingCase (
 
     if (GetBuildReference())
     {
-        CPPUNIT_ASSERT(wxCopyFile (fileName.GetFullPath(),
+         WX_ASSERT_MESSAGE(
-                                   refFileName.GetFullPath(), true));
+             ("Cannot copy file \"%s\" to \"%s\".",
+            fileName.GetFullPath(), refFileName.GetFullPath()),
+            wxCopyFile (fileName.GetFullPath(),
+                        refFileName.GetFullPath(), true));
     }
     else if (gcFactory.UseImageComparison())
     {