Improve tests for registered attributes in ExUnit
Improve tests for registered attributes in ExUnit

gfvcastro/elixir,kimshrier/elixir,kelvinst/elixir,kelvinst/elixir,lexmag/elixir,gfvcastro/elixir,michalmuskala/elixir,beedub/elixir,pedrosnk/elixir,beedub/elixir,ggcampinho/elixir,pedrosnk/elixir,kimshrier/elixir,ggcampinho/elixir,lexmag/elixir,elixir-lang/elixir,antipax/elixir,joshprice/elixir,antipax/elixir