refactored copy_if unittests
refactored copy_if unittests

sarvex/thrust,andrewcorrigan/thrust-multi-permutation-iterator,thrust/thrust,thrust/thrust,arnabgho/thrust,sdalton1/thrust,thrust/thrust,zeryx/thrust,raygit/thrust,zhenglaizhang/thrust,xiongzhanblake/thrust_src,arnabgho/thrust,jaredhoberock/thrust,sdalton1/thrust,jaredhoberock/thrust,dachziegel/thrust,zeryx/thrust,thvasilo/thrust,egaburov/thrust,egaburov/thrust,zeryx/thrust,xiongzhanblake/thrust,sdalton1/thrust,Ricardo666666/thrust,xiongzhanblake/thrust,dachziegel/thrust,GrimDerp/thrust,thvasilo/thrust,mohamed-ali/thrust,raygit/thrust,GrimDerp/thrust,jaredhoberock/thrust,mohamed-ali/thrust,xiongzhanblake/thrust_src,egaburov/thrust,dachziegel/thrust,xiongzhanblake/thrust_src,jaredhoberock/thrust,marksantos/thrust,marksantos/thrust,thrust/thrust,GrimDerp/thrust,thrust/thrust,xiongzhanblake/thrust,zhenglaizhang/thrust,andrewcorrigan/thrust-multi-permutation-iterator,arnabgho/thrust,Ricardo666666/thrust,mohamed-ali/thrust,raygit/thrust,sarvex/thrust,sarvex/thrust,marksantos/thrust,andrewcorrigan/thrust-multi-permutation-iterator,zhenglaizhang/thrust,thvasilo/thrust,jaredhoberock/thrust,Ricardo666666/thrust