Add tests for File.
Add tests for File.

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