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Allow meck:wait/{4,5,6} to be called with a condition #257

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Allow meck:wait/{4,5,6} to be called with a condition #257

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2d62c7d
Fix eqwalizer warning
rlipscombe Dec 29, 2025
526dee7
Allow meck:wait/{4,5,6} to be called with a condition
rlipscombe Dec 29, 2025
bffc6b6
Update doc comments to explain conditions
rlipscombe Dec 29, 2025
2a2c7f0
Add tests for meck:wait(Times, ...) with meck:reset
rlipscombe Dec 29, 2025
4d74823
Add tests for meck:wait(Cond, ...) with meck:reset
rlipscombe Dec 29, 2025
930a159
Add tests for meck:wait(Times, ...) with meck:reset
rlipscombe Dec 29, 2025
6487e91
Add tests for meck:wait(Cond, ...) with meck:reset
rlipscombe Dec 29, 2025
2c517fe
Fix typespec
rlipscombe Jan 22, 2026
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83 changes: 65 additions & 18 deletions src/meck.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -130,6 +130,11 @@
%% It is used in {@link expect/3} and {@link expect/4} to define a function
%% clause of complex multi-clause expectations.

-type condition_state() :: term().
-type condition_fun() :: fun((Args :: [term()], condition_state()) -> condition_state()).
-type condition() :: {condition_fun(), condition_state()}.
%% It is used in {@link wait/5} and {@link wait/6} to define a condition.

%%%============================================================================
%%% Interface exports
%%%============================================================================
Expand Down Expand Up @@ -545,7 +550,7 @@ num_calls(Mod, OptFun, OptArgsSpec, OptPid) ->
%% arguments matching `OptArgsSpec', or `Timeout' has elapsed. In the latter
%% case the call fails with `error:timeout'.
%%
%% The number of calls is counted starting from the most resent call to
%% The number of calls is counted starting from the most recent call to
%% {@link reset/1} on the mock or from the mock creation, whichever occurred
%% latter. If a matching call has already occurred, then the function returns
%% `ok' immediately.
Expand All @@ -559,35 +564,66 @@ num_calls(Mod, OptFun, OptArgsSpec, OptPid) ->
wait(Mod, OptFunc, OptArgsSpec, Timeout) ->
wait(1, Mod, OptFunc, OptArgsSpec, '_', Timeout).

%% @doc Blocks until either function `Mod:Func' is called at least `Times' with
%% arguments matching `OptArgsSpec', or `Timeout' has elapsed. In the latter
%% case the call fails with `error:timeout'.
%% @doc Blocks until function `Mod:Func' is called with arguments matching
%% `OptArgsSpec' and matching the `Condition`.
%%
%% Times out if instead `Timeout' has elapsed. In this case the call fails with
%% `error:timeout'.
%%
%% `Condition` is a tuple: `{CondFunc, CondState}`.
%%
%% On each call to `Mod:Func`, `CondFunc(Args, CondState)` is called.
%%
%% The condition function must return either `{halt, ok}` or
%% `{cont, NextCondState}`.
%%
%% In the former case, the condition is considered satisfied, and `wait`
%% returns. In the latter case, `wait` waits for further calls to `Mod:Func`.
%%
%% For backwards-compatibility, the condition can be specified as an integer.
%% This counts the number of calls to the function.
%%
%% The number of calls is counted starting from the most resent call to
%% The number of calls is counted starting from the most recent call to
%% {@link reset/1} on the mock or from the mock creation, whichever occurred
%% latter. If `Times' number of matching calls has already occurred, then the
%% function returns `ok' immediately.
%%
%% @equiv wait(Times, Mod, OptFunc, OptArgsSpec, '_', Timeout)
-spec wait(Times, Mod, OptFunc, OptArgsSpec, Timeout) -> ok when
Times :: pos_integer(),
%% @equiv wait(Condition, Mod, OptFunc, OptArgsSpec, '_', Timeout)
-spec wait(Condition, Mod, OptFunc, OptArgsSpec, Timeout) -> ok when
Condition :: pos_integer() | condition(),
Mod :: atom(),
OptFunc :: '_' | atom(),
OptArgsSpec :: '_' | args_spec(),
Timeout :: non_neg_integer().
wait(Times, Mod, OptFunc, OptArgsSpec, Timeout) ->
wait(Times, Mod, OptFunc, OptArgsSpec, '_', Timeout).
wait(Condition, Mod, OptFunc, OptArgsSpec, Timeout) ->
wait(Condition, Mod, OptFunc, OptArgsSpec, '_', Timeout).

%% @doc Blocks until either function `Mod:Func' is called at least `Times' with
%% arguments matching `OptArgsSpec' by process `OptCallerPid', or `Timeout' has
%% elapsed. In the latter case the call fails with `error:timeout'.

%% @doc Blocks until function `Mod:Func' is called with arguments matching
%% `OptArgsSpec' and matching the `Condition`.
%%
%% Times out if instead `Timeout' has elapsed. In this case the call fails with
%% `error:timeout'.
%%
%% `Condition` is a tuple: `{CondFunc, CondState}`.
%%
%% On each call to `Mod:Func`, `CondFunc(Args, CondState)` is called.
%%
%% The condition function must return either `{halt, ok}` or
%% `{cont, NextCondState}`.
%%
%% The number of calls is counted starting from the most resent call to
%% In the former case, the condition is considered satisfied, and `wait`
%% returns. In the latter case, `wait` waits for further calls to `Mod:Func`.
%%
%% For backwards-compatibility, the condition can be specified as an integer.
%% This counts the number of calls to the function.
%%
%% The number of calls is counted starting from the most recent call to
%% {@link reset/1} on the mock or from the mock creation, whichever occurred
%% latter. If `Times' number of matching call has already occurred, then the
%% latter. If `Times' number of matching calls has already occurred, then the
%% function returns `ok' immediately.
-spec wait(Times, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout) -> ok when
Times :: pos_integer(),
-spec wait(Condition, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout) -> ok when
Condition :: pos_integer() | condition(),
Mod :: atom(),
OptFunc :: '_' | atom(),
OptArgsSpec :: '_' | args_spec(),
Expand All @@ -599,7 +635,18 @@ wait(Times, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout)
when is_integer(Times) andalso Times > 0 andalso
is_integer(Timeout) andalso Timeout >= 0 ->
ArgsMatcher = meck_args_matcher:new(OptArgsSpec),
meck_proc:wait(Mod, Times, OptFunc, ArgsMatcher, OptCallerPid, Timeout).
Condition = {
fun
(_, T) when T =:= 0 -> {halt, ok};
(_, T) -> {cont, T - 1}
end,
Times - 1
},
meck_proc:wait(Mod, Condition, OptFunc, ArgsMatcher, OptCallerPid, Timeout);
wait({CondFun, _} = Condition, Mod, OptFunc, OptArgsSpec, OptCallerPid, Timeout)
when is_function(CondFun, 2) ->
ArgsMatcher = meck_args_matcher:new(OptArgsSpec),
meck_proc:wait(Mod, Condition, OptFunc, ArgsMatcher, OptCallerPid, Timeout).

%% @doc Erases the call history for a mocked module or a list of mocked modules.
%%
Expand Down
74 changes: 41 additions & 33 deletions src/meck_proc.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,10 @@
%%% Definitions
%%%============================================================================

-type condition_state() :: term().
-type condition_fun() :: fun((Args :: [term()], condition_state()) -> condition_state()).
-type condition() :: {condition_fun(), condition_state()}.

-type meck_dict() :: dict:dict().

-record(state, {mod :: atom(),
Expand All @@ -67,8 +71,8 @@
-record(tracker, {opt_func :: '_' | atom(),
args_matcher :: meck_args_matcher:args_matcher(),
opt_caller_pid :: '_' | pid(),
countdown :: non_neg_integer(),
reply_to :: {Caller::pid(), Tag::any()},
condition :: condition(),
reply_to :: gen_server:from(),
expire_at :: erlang:timestamp()}).

%%%============================================================================
Expand Down Expand Up @@ -151,21 +155,21 @@ get_history(Mod) ->
gen_server(call, Mod, get_history).

-spec wait(Mod::atom(),
Times::non_neg_integer(),
Condition::condition(),
OptFunc::'_' | atom(),
meck_args_matcher:args_matcher(),
OptCallerPid::'_' | pid(),
Timeout::non_neg_integer()) ->
ok.
wait(Mod, Times, OptFunc, ArgsMatcher, OptCallerPid, Timeout) ->
wait(Mod, {_CondFun, _CondSt} = Condition, OptFunc, ArgsMatcher, OptCallerPid, Timeout) ->
EffectiveTimeout = 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, Condition, OptFunc, ArgsMatcher, OptCallerPid,
Timeout},
EffectiveTimeout)
of
Expand Down Expand Up @@ -304,18 +308,35 @@ 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, {CondFun, CondState} = _Condition, 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, CondSt} = Acc) ->
case Filter(HistoryRec) of
true ->
{_Pid, {_M, _F, Args}, _Result} = HistoryRec,
CondFun(Args, CondSt);
false ->
Acc
end;
(_HistoryRec, {halt, _} = Acc) ->
Acc
end,
{cont, CondState},
History
),
case Result of
{halt, ok} ->
{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,
condition = {CondFun, CondState2},
reply_to = From,
expire_at = timeout_to_timestamp(Timeout)},
{noreply, S#state{trackers = [Tracker | Trackers]}}
Expand Down Expand Up @@ -687,28 +708,12 @@ cleanup(Mod) ->
code:purge(meck_util:original_name(Mod)),
Res = code:delete(meck_util:original_name(Mod)),

% `cover:export` might still export the meck generated module,
% `cover:export` might still export the meck generated module,
% make sure that does not happen.
_ = cover:reset(meck_util:original_name(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 @@ -738,7 +743,7 @@ update_tracker(Func, Args, CallerPid,
#tracker{opt_func = OptFunc,
args_matcher = ArgsMatcher,
opt_caller_pid = OptCallerPid,
countdown = Countdown,
condition = {CondFun, CondState},
reply_to = ReplyTo,
expire_at = ExpireAt} = Tracker)
when (OptFunc =:= '_' orelse Func =:= OptFunc) andalso
Expand All @@ -750,11 +755,14 @@ 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 CondFun(Args, CondState) of
{halt, ok} ->
gen_server:reply(ReplyTo, ok),
expired;
{cont, CondState2} ->
Tracker#tracker{condition = {CondFun, CondState2}}
end
end
end;
update_tracker(_Func, _Args, _CallerPid, Tracker) ->
Expand Down
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