Erlang
(page 89)
code/CustomGenerators/erlang/pbt/test/prop_generators.erl
While running property based test prop_dupes you will get the same logging info.
prop_dupes() ->
?FORALL(KV, list({key(), val()}),
begin
M = maps:from_list(KV),
_ = [maps:get(K, M) || {K, _V} <- KV], % crash if K's not in map
collect(
{dupes, to_range(5, length(KV) - length(lists:ukeysort(1,KV)))},
true
)
end).
%%%%%%%%%%%%%%%
%%% Helpers %%%
%%%%%%%%%%%%%%%
key() -> integer().
val() -> term().
to_range(M, N) ->
Base = N div M,
io:format("~2B = ~2B div ~B | {~2B, ~2B} = {~2B * ~B, (~B + 1)*~B~n",
[Base, N, M, Base * M, (Base + 1) * M, Base, M, Base, M]),
{Base * M, (Base + 1) * M}.