Tests for CompositeKey.
Tests for CompositeKey.

zhang625272514/peewee,coreos/peewee,bopo/peewee,teserak/peewee,jnovinger/peewee,d1hotpep/peewee,wenxer/peewee,new-xiaji/peewee,bopo/peewee,wenxer/peewee,jarrahwu/peewee,lez/peewee,softside/peewee,coleifer/peewee,Dipsomaniac/peewee,Sunzhifeng/peewee,fuzeman/peewee,zhang625272514/peewee,Sunzhifeng/peewee,jnovinger/peewee,coleifer/peewee,bopo/peewee,Dipsomaniac/peewee,new-xiaji/peewee,coleifer/peewee,jarrahwu/peewee,new-xiaji/peewee,Sunzhifeng/peewee,coreos/peewee,zhang625272514/peewee,py4a/peewee,mackjoner/peewee,coreos/peewee,jarrahwu/peewee,d1hotpep/peewee,ghukill/peewee,stas/peewee,Dipsomaniac/peewee,ronyb29/peewee,fuzeman/peewee