Merge pull request #224 from joedevivo/master

lager_common_test_backend

src/lager_common_test_backend.erl

@@ -0,0 +1,115 @@
+-module(lager_common_test_backend).
+
+-behavior(gen_event).
+
+%% gen_event callbacks
+-export([init/1,
+         handle_call/2,
+         handle_event/2,
+         handle_info/2,
+         terminate/2,
+         code_change/3]).
+-export([get_logs/0,
+        bounce/0,
+        bounce/1]).
+
+%% holds the log messages for retreival on terminate
+-record(state, {level :: {mask, integer()},
+                formatter :: atom(),
+                format_config :: any(),
+                log = [] :: list()}).
+
+-include("lager.hrl").
+-define(TERSE_FORMAT,[time, " ", color, "[", severity,"] ", message]).
+
+%% @doc Before every test, just
+%% lager_common_test_backend:bounce(Level) with the log level of your
+%% choice. Every message will be passed along to ct:pal for your
+%% viewing in the common_test reports. Also, you can call
+%% lager_common_test_backend:get_logs/0 to get a list of all log
+%% messages this backend has received during your test. You can then
+%% search that list for expected log messages.
+
+
+-spec get_logs() -> [iolist()] | {error, term()}.
+get_logs() ->
+    gen_event:call(lager_event, ?MODULE, get_logs, infinity).
+
+bounce() ->
+    bounce(error).
+
+bounce(Level) ->
+    application:stop(lager),
+    lager:start(),
+    gen_event:add_handler(lager_event, lager_common_test_backend, [Level, false]),
+    %lager:set_loglevel(lager_common_test_backend, Level),
+    ok.
+
+-spec(init(integer()|atom()|[term()]) -> {ok, #state{}} | {error, atom()}).
+%% @private
+%% @doc Initializes the event handler
+init([Level, true]) -> % for backwards compatibility
+    init([Level,{lager_default_formatter,[{eol, "\n"}]}]);
+init([Level,false]) -> % for backwards compatibility
+    init([Level,{lager_default_formatter,?TERSE_FORMAT ++ ["\n"]}]);
+init([Level,{Formatter,FormatterConfig}]) when is_atom(Formatter) ->
+    case lists:member(Level, ?LEVELS) of
+        true ->
+            {ok, #state{level=lager_util:config_to_mask(Level),
+                    formatter=Formatter,
+                    format_config=FormatterConfig}};
+        _ ->
+            {error, bad_log_level}
+    end;
+init(Level) ->
+    init([Level,{lager_default_formatter,?TERSE_FORMAT ++ ["\n"]}]).
+
+-spec(handle_event(tuple(), #state{}) -> {ok, #state{}}).
+%% @private
+handle_event({log, Message},
+    #state{level=L,formatter=Formatter,format_config=FormatConfig,log=Logs} = State) ->
+    case lager_util:is_loggable(Message,L,?MODULE) of
+        true ->
+            Log = Formatter:format(Message,FormatConfig),
+            ct:pal(Log),
+            {ok, State#state{log=[Log|Logs]}};
+        false ->
+            {ok, State}
+    end;
+handle_event(Event, State) ->
+    ct:pal(Event),
+    {ok, State#state{log = [Event|State#state.log]}}.
+
+-spec(handle_call(any(), #state{}) -> {ok, any(), #state{}}).
+%% @private
+%% @doc gets and sets loglevel. This is part of the lager backend api.
+handle_call(get_loglevel, #state{level=Level} = State) ->
+    {ok, Level, State};
+handle_call({set_loglevel, Level}, State) ->
+    case lists:member(Level, ?LEVELS) of
+        true ->
+            {ok, ok, State#state{level=lager_util:level_to_num(Level)}};
+        _ ->
+            {ok, {error, bad_log_level}, State}
+    end;
+handle_call(get_logs, #state{log = Logs} = State) ->
+    {ok, lists:reverse(Logs), State};
+handle_call(_, State) ->
+    {ok, ok, State}.
+
+-spec(handle_info(any(), #state{}) -> {ok, #state{}}).
+%% @private
+%% @doc gen_event callback, does nothing.
+handle_info(_, State) ->
+    {ok, State}.
+
+-spec(code_change(any(), #state{}, any()) -> {ok, #state{}}).
+%% @private
+%% @doc gen_event callback, does nothing.
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+-spec(terminate(any(), #state{}) -> {ok, list()}).
+%% @doc gen_event callback, does nothing.
+terminate(_Reason, #state{log=Logs}) ->
+    {ok, lists:reverse(Logs)}.