Erlang Maps Traversal Order Test

test_maps_order.erl

#!/usr/bin/env escript
%%% @author neerajsharma
%%% @copyright (C) 2019, Neeraj Sharma <neerajsharma.9@outlook.com>
%%% @doc
%%%
%%% @end
-module(test_maps_order).
%% -*- erlang -*-
%%

main(Args) when is_list(Args) ->
    EmulatorVersion = erlang:system_info(version),
    OtpRelease = erlang:system_info(otp_release),
    io:format("Emulator ~p, OTP Release is ~p~n",
        [EmulatorVersion, OtpRelease]),
    run_map_traversal_test(10),
    run_map_traversal_test(32),
    run_map_traversal_test(34).

run_map_traversal_test(Size) when is_integer(Size) ->
    L = [{C, C} || C <- lists:seq(1, Size)],
    M = maps:from_list(L),
    Equality = maps:keys(M) =:=
        maps:fold(fun(K, _, AccIn) -> [K | AccIn] end, [], M),
    ReverseEquality = lists:reverse(maps:keys(M)) =:=
        maps:fold(fun(K, _, AccIn) -> [K | AccIn] end, [], M),

    io:format("size=~p, Equality=~p, ReverEquality=~p~n",
        [Size, Equality, ReverseEquality]).