Add tests for native rw sub semantics.
Add tests for native rw sub semantics.

dankogai/roast,b2gills/roast,dankogai/roast,zostay/roast,b2gills/roast,bitrauser/roast,b2gills/roast,dogbert17/roast,zostay/roast,laben/roast,skids/roast,bitrauser/roast,laben/roast,niner/roast,perl6/roast,dogbert17/roast,dankogai/roast,cygx/roast,skids/roast,skids/roast,zostay/roast,niner/roast,cygx/roast,cygx/roast,laben/roast,niner/roast