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Add meck:wait_for/6 #253

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5 changes: 5 additions & 0 deletions src/meck.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@
-export([wait/4]).
-export([wait/5]).
-export([wait/6]).
-export([wait_for/6]).
-export([mocked/0]).

%% Syntactic sugar
Expand Down Expand Up @@ -601,6 +602,10 @@ wait(Times, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout)
ArgsMatcher = meck_args_matcher:new(OptArgsSpec),
meck_proc:wait(Mod, Times, OptFunc, ArgsMatcher, OptCallerPid, Timeout).

wait_for({Cond, CondState}, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout) when is_function(Cond, 2) ->
ArgsMatcher = meck_args_matcher:new(OptArgsSpec),
meck_proc:wait_for(Mod, {Cond, CondState}, OptFunc, ArgsMatcher, OptCallerPid, Timeout).

%% @doc Erases the call history for a mocked module or a list of mocked modules.
%%
%% This function will erase all calls made heretofore from the history of the
Expand Down
89 changes: 53 additions & 36 deletions src/meck_proc.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
-export([list_expects/2]).
-export([get_history/1]).
-export([wait/6]).
-export([wait_for/6]).
-export([reset/1]).
-export([validate/1]).
-export([stop/1]).
Expand Down Expand Up @@ -64,10 +65,13 @@
trackers = [] :: [tracker()],
restore = false :: boolean()}).

-type cond_state() :: term().
-type cond_fun() :: fun((Args :: [term()], cond_state()) -> cond_state()).

-record(tracker, {opt_func :: '_' | atom(),
args_matcher :: meck_args_matcher:args_matcher(),
opt_caller_pid :: '_' | pid(),
countdown :: non_neg_integer(),
awaiting :: {cond_fun(), cond_state()},
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@rlipscombe rlipscombe Apr 11, 2025

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I'm wondering whether 'awaiting' here should be 'condition'.

reply_to :: {Caller::pid(), Tag::any()},
expire_at :: erlang:timestamp()}).

Expand Down Expand Up @@ -152,14 +156,24 @@ get_history(Mod) ->
Timeout::non_neg_integer()) ->
ok.
wait(Mod, Times, OptFunc, ArgsMatcher, OptCallerPid, Timeout) ->
EffectiveTimeout = case Timeout of
0 ->
infinity;
_Else ->
Timeout
end,
Cond = fun
(_, T) when T =:= 0 ->
{halt, ok};
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@rlipscombe rlipscombe Apr 11, 2025

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halt and cont are taken from Elixir's Enum.reduce_while. The ability to return {halt, Reply} is maybe overkill, but it means that you can return something other than ok from meck:wait_for.

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@eproxus eproxus Oct 12, 2025

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Yeah, I think those are fine. It is also nice to be able to return a different return value with the state, I like that 👍

Could this code be inlined above where wait/7 is defined, then we would need one less jump?

(_, T) ->
{cont, T - 1}
end,
wait_for(Mod, {Cond, Times - 1}, OptFunc, ArgsMatcher, OptCallerPid, Timeout).

wait_for(Mod, {Cond, CondState}, OptFunc, ArgsMatcher, OptCallerPid, Timeout) ->
EffectiveTimeout =
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@rlipscombe rlipscombe Apr 11, 2025

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I just noticed that this got reformatted, making the diff bigger. I can revert just this bit, if that's wanted.

case Timeout of
0 ->
infinity;
_Else ->
Timeout
end,
Name = meck_util:proc_name(Mod),
try gen_server:call(Name, {wait, Times, OptFunc, ArgsMatcher, OptCallerPid,
try gen_server:call(Name, {wait_for, {Cond, CondState}, OptFunc, ArgsMatcher, OptCallerPid,
Timeout},
EffectiveTimeout)
of
Expand Down Expand Up @@ -297,18 +311,34 @@ handle_call(get_history, _From, S = #state{history = undefined}) ->
{reply, [], S};
handle_call(get_history, _From, S) ->
{reply, lists:reverse(S#state.history), S};
handle_call({wait, Times, OptFunc, ArgsMatcher, OptCallerPid, Timeout}, From,
handle_call({wait_for, {Cond, CondState1}, OptFunc, ArgsMatcher, OptCallerPid, Timeout}, From,
S = #state{history = History, trackers = Trackers}) ->
case times_called(OptFunc, ArgsMatcher, OptCallerPid, History) of
CalledSoFar when CalledSoFar >= Times ->
Filter = meck_history:new_filter(OptCallerPid, OptFunc, ArgsMatcher),
Result = lists:foldl(
fun(HistoryRec, {cont, CondState} = Acc) ->
case Filter(HistoryRec) of
true ->
{_Pid, {_M, _F, Args}, _Result} = HistoryRec,
Cond(Args, CondState);
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@rlipscombe rlipscombe Apr 11, 2025

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I wasn't sure whether just 'Args' was enough here, or whether also passing 'Result' would be useful. I couldn't pass the whole HistoryRec, because we don't see the whole thing when updating the tracker (unless I'm misreading that code).

false ->
Acc
end;
(_HistoryRec, {halt, _Reply} = Acc) ->
Acc
end,
{cont, CondState1},
History
),
case Result of
{halt, _Reply} ->
{reply, ok, S};
_CalledSoFar when Timeout =:= 0 ->
{cont, _} when Timeout =:= 0 ->
{reply, {error, timeout}, S};
CalledSoFar ->
{cont, CondState2} ->
Tracker = #tracker{opt_func = OptFunc,
args_matcher = ArgsMatcher,
opt_caller_pid = OptCallerPid,
countdown = Times - CalledSoFar,
awaiting = {Cond, CondState2},
reply_to = From,
expire_at = timeout_to_timestamp(Timeout)},
{noreply, S#state{trackers = [Tracker | Trackers]}}
Expand Down Expand Up @@ -668,22 +698,6 @@ cleanup(Mod) ->

Res.

-spec times_called(OptFunc::'_' | atom(),
meck_args_matcher:args_matcher(),
OptCallerPid::'_' | pid(),
meck_history:history()) ->
non_neg_integer().
times_called(OptFunc, ArgsMatcher, OptCallerPid, History) ->
Filter = meck_history:new_filter(OptCallerPid, OptFunc, ArgsMatcher),
lists:foldl(fun(HistoryRec, Acc) ->
case Filter(HistoryRec) of
true ->
Acc + 1;
_Else ->
Acc
end
end, 0, History).

-spec update_trackers(meck_history:history_record(), [tracker()]) ->
UpdTracker::[tracker()].
update_trackers(HistoryRecord, Trackers) ->
Expand Down Expand Up @@ -713,7 +727,7 @@ update_tracker(Func, Args, CallerPid,
#tracker{opt_func = OptFunc,
args_matcher = ArgsMatcher,
opt_caller_pid = OptCallerPid,
countdown = Countdown,
awaiting = {Cond, CondState},
reply_to = ReplyTo,
expire_at = ExpireAt} = Tracker)
when (OptFunc =:= '_' orelse Func =:= OptFunc) andalso
Expand All @@ -725,17 +739,20 @@ update_tracker(Func, Args, CallerPid,
case is_expired(ExpireAt) of
true ->
expired;
false when Countdown == 1 ->
gen_server:reply(ReplyTo, ok),
expired;
false ->
Tracker#tracker{countdown = Countdown - 1}
case Cond(Args, CondState) of
{halt, Result} ->
gen_server:reply(ReplyTo, Result),
expired;
{cont, CondState2} ->
Tracker#tracker{awaiting = {Cond, CondState2}}
end
end
end;
update_tracker(_Func, _Args, _CallerPid, Tracker) ->
Tracker.

-spec timeout_to_timestamp(Timeout::non_neg_integer()) -> erlang:timestamp().
-spec timeout_to_timestamp(Timeout :: non_neg_integer()) -> erlang:timestamp().
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@rlipscombe rlipscombe Apr 11, 2025

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Whoops, more reformatting noise. Can revert.

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@eproxus eproxus Oct 12, 2025

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Please do 🙂

timeout_to_timestamp(Timeout) ->
{MacroSecs, Secs, MicroSecs} = os:timestamp(),
MicroSecs2 = MicroSecs + Timeout * 1000,
Expand Down
57 changes: 57 additions & 0 deletions test/meck_tests.erl
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Expand Up @@ -1634,6 +1634,63 @@ wait_purge_expired_tracker_test() ->
%% Clean
meck:unload().

wait_for_test() ->
%% Given
meck:new(test, [non_strict]),
meck:expect(test, foo, 2, ok),
%% When
Pid = erlang:spawn(fun() ->
test:foo(1, 1),
test:foo(1, 2)
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@rlipscombe rlipscombe Apr 11, 2025

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It occurs that these tests don't actually address the "any order / grouping" motivation. I can add more tests if the general approach looks sensible.

end),
%% Then
Cond = fun([_A, B], Expected) ->
case Expected -- [B] of
[] -> {halt, ok};
Remaining -> {cont, Remaining}
end
end,
meck:wait_for(
{Cond, [1, 2]},
test,
foo,
['_', '_'],
Pid,
1
),
%% Clean
meck:unload().

wait_for_fails_test() ->
%% Given
meck:new(test, [non_strict]),
meck:expect(test, foo, 2, ok),
%% When
Pid = erlang:spawn(fun() ->
test:foo(1, 1),
test:foo(1, 2)
end),
%% Then
Cond = fun([_A, B], Expected) ->
case Expected -- [B] of
[] -> {halt, ok};
Remaining -> {cont, Remaining}
end
end,
?assertError(
timeout,
meck:wait_for(
{Cond, [1, 2, 3]},
test,
foo,
['_', '_'],
Pid,
1
)
),
%% Clean
meck:unload().

mocked_test() ->
%% At start, no modules should be mocked:
[] = meck:mocked(),
Expand Down