Add tests for size, update and empty
Add tests for size, update and empty

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