src/couch_log/test/eunit/couch_log_config_listener_test.erl

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-module(couch_log_config_listener_test).

-include_lib("couch_log/include/couch_log.hrl").
-include_lib("eunit/include/eunit.hrl").

-define(TIMEOUT, 1000).

couch_log_config_test_() ->
    {setup, fun couch_log_test_util:start/0, fun couch_log_test_util:stop/1, [
        fun check_restart_listener/0,
        fun check_ignore_non_log/0,
        fun check_only_one_couch_error_handler/0
    ]}.

check_restart_listener() ->
    Listener1 = get_listener(),
    ?assert(is_process_alive(Listener1)),

    Handler1 = get_handler(),
    ?assertNotEqual(not_found, Handler1),
    Ref = erlang:monitor(process, Listener1),
    ok = gen_event:delete_handler(config_event, get_handler(), testing),

    receive
        {'DOWN', Ref, process, _, _} ->
            ?assertNot(is_process_alive(Listener1))
    after ?TIMEOUT ->
        erlang:error({timeout, config_listener_mon_death})
    end,

    NewHandler = test_util:wait(
        fun() ->
            case get_handler() of
                not_found -> wait;
                Reply -> Reply
            end
        end,
        ?TIMEOUT,
        20
    ),
    ?assertEqual(Handler1, NewHandler),

    Listener2 = get_listener(),
    ?assert(is_process_alive(Listener2)),
    ?assertNotEqual(Listener1, Listener2),
    ok.

check_ignore_non_log() ->
    Run = fun() ->
        couch_log_test_util:with_config_listener(fun() ->
            config:set("foo", "bar", "baz"),
            couch_log_test_util:wait_for_config()
        end)
    end,
    ?assertError(config_change_timeout, Run()).

check_only_one_couch_error_handler() ->
    Handlers = gen_event:which_handlers(error_logger),
    CouchHandlers = [H || H <- Handlers, H =:= couch_log_error_logger_h],
    ?assertEqual(1, length(CouchHandlers)).

get_handler() ->
    FoldFun = fun
        ({config_listener, {couch_log_sup, _}} = H, not_found) ->
            H;
        (_, Acc) ->
            Acc
    end,
    lists:foldl(FoldFun, not_found, gen_event:which_handlers(config_event)).

get_listener() ->
    Children = supervisor:which_children(couch_log_sup),
    hd([Pid || {config_listener_mon, Pid, _, _} <- Children]).