add a test with :empty with Composition to make sure it works. fixes #75.
add a test with :empty with Composition to make sure it works. fixes #75.

prosanelli/reform,gdott9/reform,eljojo/reform,mipearson/reform,prosanelli/reform,swifthand/reform,halan/reform,Miralaw/reform,apotonick/reform,halan/reform,eljojo/reform,bolshakov/reform,joealba/reform,mipearson/reform,swifthand/reform,joealba/reform,simonc/reform,francirp/reform,francirp/reform,bolshakov/reform,trailblazer/reform,Miralaw/reform