Add specs for DataMapper::Engine#adapter
Add specs for DataMapper::Engine#adapter

pxlpnk/rom,endash/rom,rom-rb/rom,denyago/rom,dekz/rom,cored/rom,pdswan/rom,pvcarrera/rom,rom-rb/rom,kwando/rom,vrish88/rom,dcarral/rom,Snuff/rom,rom-rb/rom,jeremyf/rom