Add some more record printing tests and fix a bug

src/lager.erl

@@ -282,7 +282,7 @@ pr(Record, Module) when is_tuple(Record), is_atom(element(1, Record)) ->
                                 (_) ->
                                     false
                             end, Records) of
-                        false ->
+                        [] ->
                             Record;
                         [{RecordName, RecordFields}|_] ->
                             {'$lager_record', RecordName,

test/lager_test_backend.erl

@@ -55,6 +55,10 @@ handle_call(print_state, State) ->
     spawn(fun() -> lager:info("State ~p", [lager:pr(State, ?MODULE)]) end),
     timer:sleep(100),
     {ok, ok, State};
+handle_call(print_bad_state, State) ->
+    spawn(fun() -> lager:info("State ~p", [lager:pr({state, 1}, ?MODULE)]) end),
+    timer:sleep(100),
+    {ok, ok, State};
 handle_call(_Request, State) ->
     {ok, ok, State}.
 
@@ -96,6 +100,9 @@ flush() ->
 print_state() ->
     gen_event:call(lager_event, ?MODULE, print_state).
 
+print_bad_state() ->
+    gen_event:call(lager_event, ?MODULE, print_bad_state).
+
 has_line_numbers() ->
     %% are we R15 or greater
     Rel = erlang:system_info(otp_release),
@@ -236,6 +243,45 @@ lager_test_() ->
                         ?assertEqual("State #state{level=6,buffer=[],ignored=[]}", lists:flatten(Message)),
                         ok
                 end
+            },
+            {"record printing fails gracefully",
+                fun() ->
+                        print_bad_state(),
+                        {Level, _Time, Message, _Metadata}  = pop(),
+                        ?assertMatch(Level, lager_util:level_to_num(info)),
+                        ?assertEqual("State {state,1}", lists:flatten(Message)),
+                        ok
+                end
+            },
+            {"record printing fails gracefully when no lager_record attribute",
+                fun() ->
+                        spawn(fun() -> lager:info("State ~p", [lager:pr({state, 1}, lager)]) end),
+                        timer:sleep(100),
+                        {Level, _Time, Message, _Metadata}  = pop(),
+                        ?assertMatch(Level, lager_util:level_to_num(info)),
+                        ?assertEqual("State {state,1}", lists:flatten(Message)),
+                        ok
+                end
+            },
+            {"record printing fails gracefully when input is not a tuple",
+                fun() ->
+                        spawn(fun() -> lager:info("State ~p", [lager:pr(ok, lager)]) end),
+                        timer:sleep(100),
+                        {Level, _Time, Message, _Metadata}  = pop(),
+                        ?assertMatch(Level, lager_util:level_to_num(info)),
+                        ?assertEqual("State ok", lists:flatten(Message)),
+                        ok
+                end
+            },
+            {"record printing fails gracefully when module is invalid",
+                fun() ->
+                        spawn(fun() -> lager:info("State ~p", [lager:pr({state, 1}, not_a_module)]) end),
+                        timer:sleep(100),
+                        {Level, _Time, Message, _Metadata}  = pop(),
+                        ?assertMatch(Level, lager_util:level_to_num(info)),
+                        ?assertEqual("State {state,1}", lists:flatten(Message)),
+                        ok
+                end
             }
         ]
     }.