Yet Another Erlang/Unicode Fuckup

reduced_test_case.erl

-module(reduced_test_case).

-define(NODEBUG, 1).
-include_lib("eunit/include/eunit.hrl").

-behavior(gen_server).

%-compile(export_all).
-export([init/1, code_change/3, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
-export([start/0]).

-define(SERVER, ?MODULE).

start() ->
        {ok, PID} = gen_server:start_link({local, ?SERVER}, ?MODULE, [], []),
        PID ! {hi, [1040,1044]},                                        % try a string/list
        PID ! {hi, <<"\xa9">>},                                         % try a latin1 binary
        PID ! {hi, <<"\xd0\x90\xd0\x94">>},                             % try a utf8 binary
        PID ! {hi, [[1040,1044], <<"\xa9">>, <<"\xd0\x90\xd0\x94">>]},  % all together in a iolist
        {ok, PID}.


to_binary(IoList) when is_binary(IoList) ->
    IoList;

to_binary(IoList) ->
    to_binary(IoList, []).

to_binary([], Acc) ->
    Acc;

to_binary([Head | Tail], Acc) when is_binary(Head) ->
    to_binary(Tail, [Acc | Head]);

to_binary(IoList, Acc) ->
    case unicode:characters_to_binary(IoList) of
        {error, Bin, Rest} ->
            to_binary(Rest, [Acc|Bin]);
        {incomplete, Bin1, Bin2} ->
            [Acc | [Bin1, Bin2]];
        Bin ->
            Bin
    end.

print(Data) ->
    port_command(stdout, [to_binary(Data), "\n"]).

init(_) ->
    StdOut = open_port("/dev/stdout", [binary, out]),
    register(stdout, StdOut),
    {ok, []}.


handle_info({hi, Data}, State) ->
    print(Data),
    {noreply, State};


handle_info(_Msg, State) -> {noreply, State}.
handle_call(_Msg, _Caller, State) -> {noreply, State}.
handle_cast(_Msg, State) -> {noreply, State}.
terminate(_Reason, _State) -> ok.
code_change(_OldVersion, State, _Extra) -> {ok, State}.

test.sh

echo "Reduced test case:"
cat reduced_test_case.erl
erlc reduced_test_case.erl
echo
echo "==="
echo "Running erl -eval \"reduced_test_case:start()\" with keys"
echo "* -run init stop"
echo
echo "<output>"
erl -eval "reduced_test_case:start()" -run init stop
echo "</output>"
echo
echo
echo "==="
echo "Running erl -eval \"reduced_test_case:start()\" with keys"
echo "* -run init stop -noshell"
echo
echo "<output>"
erl -eval "reduced_test_case:start()" -run init stop -noshell
echo "</output>"
echo
echo
echo
echo "Feel the difference."

be careful though, that to_binary recursive function has a bug where it enters an infinite loop in some cases. In the end I've decided not to use it.