BowlingGameKata in Erlang 2

.gitignore

*.beam

bowling_game.erl

-module(bowling_game).
-export([score/1]).

score(Rolls) -> score(0, Rolls).

%% All rolls processed
score(Score, []) -> Score;

%% 10th frame
score(Score, [X, Y, Z]) -> Score + X + Y + Z;

%% Strike
score(Score, [10 | Rest]) ->
    score(Score + 10 + bonus(Rest, 2), Rest);

%% Spare
score(Score, [X, Y | Rest]) when X + Y =:= 10 ->
    score(Score + 10 + bonus(Rest, 1), Rest);

%% Not strike nor spare
score(Score, [X, Y | Rest]) when X + Y =/= 10 ->
    score(Score + X + Y, Rest).

bonus(_, 0) -> 0;
bonus([], _) -> 0;
bonus([Roll | Rest], N) -> Roll + bonus(Rest, N - 1).

bowling_game_test.erl

-module(bowling_game_test).
-include_lib("eunit/include/eunit.hrl").

gutter_rolls() -> lists:duplicate(20, 0).
all_one_rolls() -> lists:duplicate(20, 1).
one_spare_rolls() -> [5, 5, 3] ++ lists:duplicate(17, 0).
one_spare_rolls2() -> [0, 0, 3, 7, 7] ++ lists:duplicate(15, 0).
one_strike_rolls() -> [10, 3, 4] ++ lists:duplicate(16, 0).
perfect_game_rolls() -> lists:duplicate(12, 10).

gutter_game_test() ->
    ?assertEqual(0, bowling_game:score(gutter_rolls())).

all_ones_test() ->
    ?assertEqual(20, bowling_game:score(all_one_rolls())).

one_spare_test() ->
    ?assertEqual(16, bowling_game:score(one_spare_rolls())).

one_spare_another_test() ->
    ?assertEqual(24, bowling_game:score(one_spare_rolls2())).

one_strike_test() ->
    ?assertEqual(24, bowling_game:score(one_strike_rolls())).

perfect_game_test() ->
    ?assertEqual(300, bowling_game:score(perfect_game_rolls())).