file_formatter_spec: simplify tests a bit
file_formatter_spec: simplify tests a bit

* simplify test names

* use described_class instead of the actual name.
  It's shorter.

caporta/pry,scalixte-mdsol/pry,ooohiroyukiooo/pry,ngpestelos/pry,bronzdoc/pry,caporta/pry,tdg5/pry,pvdb/pry,scalixte-mdsol/pry,jasonm23/pry,ooohiroyukiooo/pry,printercu/pry,josue804/debunker,gfvcastro/pry,jasnow/pry,raeno/pry,bronzdoc/pry,raeno/pry,shockone/pry,ooohiroyukiooo/pry,shockone/pry,tdg5/pry,pvdb/pry,85x14/pry,shockone/pry,85x14/pry,printercu/pry,jasonm23/pry,jasonm23/pry,geoffreylitt/pry,gfvcastro/pry,nju520/pry,nju520/pry,icebreaker/pry,geoffreylitt/pry,tdg5/pry,jasnow/pry,josue804/debunker,raeno/pry,85x14/pry,nju520/pry,icebreaker/pry,scalixte-mdsol/pry,ngpestelos/pry,caporta/pry,jasnow/pry