Use of proper to test a simple regex

tmp.erl

-module (tmp).

-include_lib ("proper/include/proper.hrl").

prop_all () ->
  ?FORALL (Int, non_neg_integer(),
           begin
               {match, [O]} =
                 re:run (integer_to_list(Int), <<"[0-9]+">>,
                   [{capture,first,list}]),
               Int =:= list_to_integer (O)
           end).