wip

13 files changed, 653 insertions, 0 deletions

diff --git a/learn-you-some-erlang/reminder/Emakefile b/learn-you-some-erlang/reminder/Emakefile
new file mode 100644
index 0000000..fbde9cb
--- /dev/null
+++ b/learn-you-some-erlang/reminder/Emakefile
@@ -0,0 +1,4 @@
+{'src/*', [debug_info,
+           {i, "src"},
+           {i, "include"},
+           {outdir, "ebin"}]}.
diff --git a/learn-you-some-erlang/reminder/ebin/.this-file-intentionally-left-blank b/learn-you-some-erlang/reminder/ebin/.this-file-intentionally-left-blank
new file mode 100644
index 0000000..758f532
--- /dev/null
+++ b/learn-you-some-erlang/reminder/ebin/.this-file-intentionally-left-blank
@@ -0,0 +1 @@
+Thank you, Mercurial! I still love you...
diff --git a/learn-you-some-erlang/reminder/include/.this-file-intentionally-left-blank b/learn-you-some-erlang/reminder/include/.this-file-intentionally-left-blank
new file mode 100644
index 0000000..758f532
--- /dev/null
+++ b/learn-you-some-erlang/reminder/include/.this-file-intentionally-left-blank
@@ -0,0 +1 @@
+Thank you, Mercurial! I still love you...
diff --git a/learn-you-some-erlang/reminder/priv/.this-file-intentionally-left-blank b/learn-you-some-erlang/reminder/priv/.this-file-intentionally-left-blank
new file mode 100644
index 0000000..758f532
--- /dev/null
+++ b/learn-you-some-erlang/reminder/priv/.this-file-intentionally-left-blank
@@ -0,0 +1 @@
+Thank you, Mercurial! I still love you...
diff --git a/learn-you-some-erlang/reminder/src/.this-file-intentionally-left-blank b/learn-you-some-erlang/reminder/src/.this-file-intentionally-left-blank
new file mode 100644
index 0000000..758f532
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/.this-file-intentionally-left-blank
@@ -0,0 +1 @@
+Thank you, Mercurial! I still love you...
diff --git a/learn-you-some-erlang/reminder/src/dev_event.erl b/learn-you-some-erlang/reminder/src/dev_event.erl
new file mode 100644
index 0000000..5b752ac
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/dev_event.erl
@@ -0,0 +1,82 @@
+%%% This module is there to test the incomplete loops and constructs
+%%% that are presented in the text, but are not the final result.
+-module(dev_event).
+-compile(export_all).
+-record(state, {server,
+                name="",
+                to_go=0}).
+
+start1(EventName, Delay) ->
+    spawn(?MODULE, init1, [self(), EventName, Delay]).
+
+start_link1(EventName, Delay) ->
+    spawn_link(?MODULE, init1, [self(), EventName, Delay]).
+
+start2(EventName, Delay) ->
+    spawn(?MODULE, init2, [self(), EventName, Delay]).
+
+start_link2(EventName, Delay) ->
+    spawn_link(?MODULE, init2, [self(), EventName, Delay]).
+
+cancel(Pid) ->
+    %% Monitor in case the process is already dead
+    Ref = erlang:monitor(process, Pid),
+    Pid ! {self(), Ref, cancel},
+    receive
+        {Ref, ok} ->
+            erlang:demonitor(Ref, [flush]),
+            ok;
+        {'DOWN', Ref, process, Pid, _Reason} ->
+            ok
+    end.
+
+
+
+%%% Event's innards
+init1(Server, EventName, Delay) ->
+    loop2(#state{server=Server,
+                name=EventName,
+                to_go=normalize(Delay)}).
+
+init2(Server, EventName, DateTime) ->
+    loop2(#state{server=Server,
+                name=EventName,
+                to_go=time_to_go(DateTime)}).
+
+loop1(S = #state{server=Server}) ->
+    receive
+        {Server, Ref, cancel} ->
+            Server ! {Ref, ok}
+    after S#state.to_go * 1000 ->
+        Server ! {done, S#state.name}
+    end.
+
+%% Loop uses a list for times in order to go around the ~49 days limit
+%% on timeouts.
+loop2(S = #state{server=Server, to_go=[T|Next]}) ->
+    receive
+        {Server, Ref, cancel} ->
+            Server ! {Ref, ok}
+    after T*1000 ->
+        if Next =:= [] ->
+            Server ! {done, S#state.name};
+           Next =/= [] ->
+            loop2(S#state{to_go=Next})
+        end
+    end.
+
+
+time_to_go(TimeOut={{_,_,_}, {_,_,_}}) ->
+    Now = calendar:local_time(),
+    ToGo = calendar:datetime_to_gregorian_seconds(TimeOut) -
+           calendar:datetime_to_gregorian_seconds(Now),
+    Secs = if ToGo > 0  -> ToGo;
+              ToGo =< 0 -> 0
+           end,
+    normalize(Secs).
+
+%% Because Erlang is limited to about 49 days (49*24*60*60*1000) in
+%% milliseconds, the following function is used
+normalize(N) ->
+    Limit = 49*24*60*60,
+    [N rem Limit | lists:duplicate(N div Limit, Limit)].
diff --git a/learn-you-some-erlang/reminder/src/event.erl b/learn-you-some-erlang/reminder/src/event.erl
new file mode 100644
index 0000000..58b5b57
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/event.erl
@@ -0,0 +1,61 @@
+-module(event).
+-export([start/2, start_link/2, cancel/1]).
+-export([init/3, loop/1]).
+-record(state, {server,
+                name="",
+                to_go=0}).
+
+%%% Public interface
+start(EventName, DateTime) ->
+    spawn(?MODULE, init, [self(), EventName, DateTime]).
+
+start_link(EventName, DateTime) ->
+    spawn_link(?MODULE, init, [self(), EventName, DateTime]).
+
+cancel(Pid) ->
+    %% Monitor in case the process is already dead
+    Ref = erlang:monitor(process, Pid),
+    Pid ! {self(), Ref, cancel},
+    receive
+        {Ref, ok} ->
+            erlang:demonitor(Ref, [flush]),
+            ok;
+        {'DOWN', Ref, process, Pid, _Reason} ->
+            ok
+    end.
+
+%%% Event's innards
+init(Server, EventName, DateTime) ->
+    loop(#state{server=Server,
+                name=EventName,
+                to_go=time_to_go(DateTime)}).
+
+%% Loop uses a list for times in order to go around the ~49 days limit
+%% on timeouts.
+loop(S = #state{server=Server, to_go=[T|Next]}) ->
+    receive
+        {Server, Ref, cancel} ->
+            Server ! {Ref, ok}
+    after T*1000 ->
+        if Next =:= [] ->
+            Server ! {done, S#state.name};
+           Next =/= [] ->
+            loop(S#state{to_go=Next})
+        end
+    end.
+
+%%% private functions
+time_to_go(TimeOut={{_,_,_}, {_,_,_}}) ->
+    Now = calendar:local_time(),
+    ToGo = calendar:datetime_to_gregorian_seconds(TimeOut) -
+           calendar:datetime_to_gregorian_seconds(Now),
+    Secs = if ToGo > 0  -> ToGo;
+              ToGo =< 0 -> 0
+           end,
+    normalize(Secs).
+
+%% Because Erlang is limited to about 49 days (49*24*60*60*1000) in
+%% milliseconds, the following function is used
+normalize(N) ->
+    Limit = 49*24*60*60,
+    [N rem Limit | lists:duplicate(N div Limit, Limit)].
diff --git a/learn-you-some-erlang/reminder/src/evserv.erl b/learn-you-some-erlang/reminder/src/evserv.erl
new file mode 100644
index 0000000..1087376
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/evserv.erl
@@ -0,0 +1,168 @@
+%% Event server
+-module(evserv).
+-compile(export_all).
+
+-record(state, {events,    %% list of #event{} records
+                clients}). %% list of Pids
+
+-record(event, {name="",
+                description="",
+                pid,
+                timeout={{1970,1,1},{0,0,0}}}).
+
+%%% User Interface
+
+start() ->
+    register(?MODULE, Pid=spawn(?MODULE, init, [])),
+    Pid.
+
+start_link() ->
+    register(?MODULE, Pid=spawn_link(?MODULE, init, [])),
+    Pid.
+
+terminate() ->
+    ?MODULE ! shutdown.
+
+init() ->
+    %% Loading events from a static file could be done here.
+    %% You would need to pass an argument to init (maybe change the functions
+    %% start/0 and start_link/0 to start/1 and start_link/1) telling where the
+    %% resource to find the events is. Then load it from here.
+    %% Another option is to just pass the event straight to the server
+    %% through this function.
+    loop(#state{events=orddict:new(),
+                clients=orddict:new()}).
+
+subscribe(Pid) ->
+    Ref = erlang:monitor(process, whereis(?MODULE)),
+    ?MODULE ! {self(), Ref, {subscribe, Pid}},
+    receive
+        {Ref, ok} ->
+            {ok, Ref};
+        {'DOWN', Ref, process, _Pid, Reason} ->
+            {error, Reason}
+    after 5000 ->
+        {error, timeout}
+    end.
+
+add_event(Name, Description, TimeOut) ->
+    Ref = make_ref(),
+    ?MODULE ! {self(), Ref, {add, Name, Description, TimeOut}},
+    receive
+        {Ref, Msg} -> Msg
+    after 5000 ->
+        {error, timeout}
+    end.
+
+add_event2(Name, Description, TimeOut) ->
+    Ref = make_ref(),
+    ?MODULE ! {self(), Ref, {add, Name, Description, TimeOut}},
+    receive
+        {Ref, {error, Reason}} -> erlang:error(Reason);
+        {Ref, Msg} -> Msg
+    after 5000 ->
+        {error, timeout}
+    end.
+
+cancel(Name) ->
+    Ref = make_ref(),
+    ?MODULE ! {self(), Ref, {cancel, Name}},
+    receive
+        {Ref, ok} -> ok
+    after 5000 ->
+        {error, timeout}
+    end.
+
+listen(Delay) ->
+    receive
+        M = {done, _Name, _Description} ->
+            [M | listen(0)]
+    after Delay*1000 ->
+        []
+    end.
+
+%%% The Server itself
+
+loop(S=#state{}) ->
+    receive
+        {Pid, MsgRef, {subscribe, Client}} ->
+            Ref = erlang:monitor(process, Client),
+            NewClients = orddict:store(Ref, Client, S#state.clients),
+            Pid ! {MsgRef, ok},
+            loop(S#state{clients=NewClients});
+        {Pid, MsgRef, {add, Name, Description, TimeOut}} ->
+            case valid_datetime(TimeOut) of
+                true ->
+                    EventPid = event:start_link(Name, TimeOut),
+                    NewEvents = orddict:store(Name,
+                                              #event{name=Name,
+                                                     description=Description,
+                                                     pid=EventPid,
+                                                     timeout=TimeOut},
+                                              S#state.events),
+                    Pid ! {MsgRef, ok},
+                    loop(S#state{events=NewEvents});
+                false ->
+                    Pid ! {MsgRef, {error, bad_timeout}},
+                    loop(S)
+            end;
+        {Pid, MsgRef, {cancel, Name}} ->
+            Events = case orddict:find(Name, S#state.events) of
+                         {ok, E} ->
+                             event:cancel(E#event.pid),
+                             orddict:erase(Name, S#state.events);
+                         error ->
+                             S#state.events
+                     end,
+            Pid ! {MsgRef, ok},
+            loop(S#state{events=Events});
+        {done, Name} ->
+            case orddict:find(Name, S#state.events) of
+                {ok, E} ->
+                    send_to_clients({done, E#event.name, E#event.description},
+                                    S#state.clients),
+                    NewEvents = orddict:erase(Name, S#state.events),
+                    loop(S#state{events=NewEvents});
+                error ->
+                    %% This may happen if we cancel an event and
+                    %% it fires at the same time
+                    loop(S)
+            end;
+        shutdown ->
+            exit(shutdown);
+        {'DOWN', Ref, process, _Pid, _Reason} ->
+            loop(S#state{clients=orddict:erase(Ref, S#state.clients)});
+        code_change ->
+            ?MODULE:loop(S);
+        {Pid, debug} -> %% used as a hack to let me do some unit testing
+            Pid ! S,
+            loop(S);
+        Unknown ->
+            io:format("Unknown message: ~p~n",[Unknown]),
+            loop(S)
+    end.
+
+
+%%% Internal Functions
+send_to_clients(Msg, ClientDict) ->
+    orddict:map(fun(_Ref, Pid) -> Pid ! Msg end, ClientDict).
+
+valid_datetime({Date,Time}) ->
+    try
+        calendar:valid_date(Date) andalso valid_time(Time)
+    catch
+        error:function_clause -> %% not in {{Y,M,D},{H,Min,S}} format
+            false
+    end;
+valid_datetime(_) ->
+    false.
+
+%% calendar has valid_date, but nothing for days.
+%% This function is based on its interface.
+%% Ugly, but ugh.
+valid_time({H,M,S}) -> valid_time(H,M,S).
+
+valid_time(H,M,S) when H >= 0, H < 24,
+                       M >= 0, M < 60,
+                       S >= 0, S < 60 -> true;
+valid_time(_,_,_) -> false.
diff --git a/learn-you-some-erlang/reminder/src/sup.erl b/learn-you-some-erlang/reminder/src/sup.erl
new file mode 100644
index 0000000..71a463b
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/sup.erl
@@ -0,0 +1,22 @@
+-module(sup).
+-export([start/2, start_link/2, init/1, loop/1]).
+
+start(Mod, Args) ->
+    spawn(?MODULE, init, [{Mod, Args}]).
+
+start_link(Mod,Args) ->
+    spawn_link(?MODULE, init, [{Mod, Args}]).
+
+init({Mod,Args}) ->
+    process_flag(trap_exit, true),
+    loop({Mod,start_link,Args}).
+
+loop({M,F,A}) ->
+    Pid = apply(M,F,A),
+    receive
+        {'EXIT', _From, shutdown} ->
+            exit(shutdown); % will kill the child too
+        {'EXIT', Pid, Reason} ->
+            io:format("Process ~p exited for reason ~p~n",[Pid,Reason]),
+            loop({M,F,A})
+    end.
diff --git a/learn-you-some-erlang/reminder/src/tests/dev_event_tests.erl b/learn-you-some-erlang/reminder/src/tests/dev_event_tests.erl
new file mode 100644
index 0000000..5de18d1
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/tests/dev_event_tests.erl
@@ -0,0 +1,41 @@
+-module(dev_event_tests).
+-include_lib("eunit/include/eunit.hrl").
+%%% Very minimal tests, only verifying that the two implementations of
+%%% timeouts work the same in their final and primitive versions
+%%% as in the final module. The rest is rather cruft to emulate the normal
+%%% event.erl module. Little is tested, because little needs to be tested.
+
+
+-record(state, {server,
+                name="",
+                to_go=[0]}).
+
+timeout_test_() ->
+    {inorder,
+     [fun() -> timeout(loop1, 2) end,
+      fun() -> timeout(loop2, [2]) end]}.
+
+timeout(AtomFun, T) ->
+    S = self(),
+    spawn_link(dev_event, AtomFun, [#state{server=S, name="test", to_go=T}]),
+    timer:sleep(1000),
+    M1 = receive A -> A after 0 -> timeout end,
+    timer:sleep(1500),
+    M2 = receive B -> B after 0 -> timeout end,
+    M3 = receive C -> C after 0 -> timeout end,
+    ?assertEqual(timeout, M1),
+    ?assertEqual({done, "test"}, M2),
+    ?assertEqual(timeout, M3).
+
+cancel_msg_test_() ->
+    {inorder, 
+     [fun() -> cancel_msg(loop1, 2) end,
+      fun() -> cancel_msg(loop2, [2]) end]}.
+
+cancel_msg(AtomFun, T) ->
+    S = self(),
+    R = make_ref(),
+    Pid = spawn_link(dev_event, AtomFun, [#state{server=S, name="test", to_go=T}]),
+    Pid ! {S, R, cancel},
+    M = receive A -> A after 500 -> timeout end,
+    ?assertEqual({R, ok}, M).
diff --git a/learn-you-some-erlang/reminder/src/tests/event_tests.erl b/learn-you-some-erlang/reminder/src/tests/event_tests.erl
new file mode 100644
index 0000000..80b3a44
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/tests/event_tests.erl
@@ -0,0 +1,43 @@
+-module(event_tests).
+-include_lib("eunit/include/eunit.hrl").
+-test_warnings([start/0, start_link/1, init/0, time_to_go/1]).
+%% defined in event.erl
+-record(state, {server,
+                name="",
+                to_go=[0]}).
+
+timeout_test_() ->
+    S = self(),
+    spawn_link(event, loop, [#state{server=S, name="test", to_go=[2]}]),
+    timer:sleep(1000),
+    M1 = receive A -> A after 0 -> timeout end,
+    timer:sleep(1500),
+    M2 = receive B -> B after 0 -> timeout end,
+    M3 = receive C -> C after 0 -> timeout end,
+    [?_assertEqual(timeout, M1),
+     ?_assertEqual({done, "test"}, M2),
+     ?_assertEqual(timeout, M3)].
+
+cancel_msg_test_() ->
+    S = self(),
+    R = make_ref(),
+    Pid = spawn_link(event, loop, [#state{server=S, name="test", to_go=[2]}]),
+    Pid ! {S, R, cancel},
+    M = receive A -> A after 500 -> timeout end,
+    [?_assertEqual({R, ok}, M)].
+
+cancel_fn_test_() ->
+    S = self(),
+    Pid = spawn_link(event, loop, [#state{server=S, name="test", to_go=[2]}]),
+    [?_assertEqual(ok, event:cancel(Pid)),
+     %% calling cancel again should fail, but still return ok.
+     ?_assertEqual(ok, event:cancel(Pid))].
+
+normalize_test_() ->
+    [?_assertEqual([0], event:normalize(0)),
+     ?_assertEqual([2], event:normalize(2)),
+     %% special cases w/ remainders
+     ?_assertEqual(1, length(event:normalize(49*24*60*59))),
+     ?_assertEqual(2, length(event:normalize(49*24*60*60))),
+     ?_assertEqual(2, length(event:normalize(49*24*60*60+1))),
+     ?_assertEqual(1000*24*60*60, lists:sum(event:normalize(1000*24*60*60)))].
diff --git a/learn-you-some-erlang/reminder/src/tests/evserv_tests.erl b/learn-you-some-erlang/reminder/src/tests/evserv_tests.erl
new file mode 100644
index 0000000..b093a58
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/tests/evserv_tests.erl
@@ -0,0 +1,203 @@
+-module(evserv_tests).
+-include_lib("eunit/include/eunit.hrl").
+-define(FUTURE_DATE, {{2100,1,1},{0,0,0}}).
+%% all the tests in this module would be much easier with property-based testing.
+%% see Triq, Quvic Quickcheck or Proper for libraries to download that let you
+%% do this.
+-test_warnings([start/0]).
+
+valid_time_test_() ->
+    [?_assert(evserv:valid_time({0,0,0})),
+     ?_assert(evserv:valid_time({23,59,59})),
+     ?_assert(not evserv:valid_time({23,59,60})),
+     ?_assert(not evserv:valid_time({23,60,59})),
+     ?_assert(not evserv:valid_time({24,59,59})),
+     ?_assert(not evserv:valid_time({-1,0,0})),
+     ?_assert(not evserv:valid_time({0,-1,0})),
+     ?_assert(not evserv:valid_time({0,0,-1}))].
+
+valid_datetime_test_() ->
+    [?_assert(evserv:valid_datetime({{0,1,1},{0,0,0}})),
+     ?_assert(evserv:valid_datetime({{2004,2,29},{23,59,59}})),
+     ?_assert(evserv:valid_datetime({{2004,12,31},{23,59,59}})),
+     ?_assert(not evserv:valid_datetime({{2004,12,31},{23,60,60}})),
+     ?_assert(not evserv:valid_datetime({{2003,2,29},{23,59,59}})),
+     ?_assert(not evserv:valid_datetime({{0,0,0},{0,0,0}})),
+     ?_assert(not evserv:valid_datetime(1209312303))].
+
+loop_test_() ->
+    {"Testing all server events on a protocol level",
+     [{"Subscribe Tests",
+       [{spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun subscribe/1}},
+        {spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun subscribe2/1}},
+        {spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun down/1}}]},
+      {"Adding event integration tests",
+       [{spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun add/1}},
+        {spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun addremove/1}},
+        {spawn,
+         {setup,
+          fun evserv:start_link/0,
+          fun terminate/1,
+          fun done/1}}]}]}.
+
+interface_test_() ->
+    {"Testing all server events via the interface functions",
+     [{spawn,
+       {setup,
+        fun evserv:start_link/0,
+        fun terminate/1,
+        fun interface/1}}]}.
+
+subscribe(Pid) ->
+    Ref = make_ref(),
+    S = self(),
+    Pid ! {S, Ref, {subscribe, S}},
+    {ok, M1} = read(),
+    Pid ! {S, debug},
+    {ok, M2} = read(),
+    [?_assertEqual({Ref, ok}, M1),
+     ?_assertMatch({state,[], [{_, S}]}, M2)].
+
+subscribe2(Pid) ->
+    Ref1 = make_ref(),
+    Ref2 = make_ref(),
+    S = self(),
+    Pid ! {S, Ref1, {subscribe, S}},
+    {ok, M1} = read(),
+    Pid ! {S, Ref2, {subscribe, S}},
+    {ok, M2} = read(),
+    Pid ! {S, debug},
+    {ok, M3} = read(),
+    [?_assertEqual({Ref1, ok}, M1),
+     ?_assertEqual({Ref2, ok}, M2),
+     ?_assertMatch({state,[], [{_,S},{_,S}]}, M3)].
+
+down(Pid) ->
+    Ref = make_ref(),
+    ClientPid = spawn(fun() -> timer:sleep(50000) end),
+    Pid ! {self(), debug},
+    {ok, S1} = read(),
+    Pid ! {self(), Ref, {subscribe, ClientPid}},
+    {ok, M1} = read(),
+    Pid ! {self(), debug},
+    {ok, S2} = read(),
+    exit(ClientPid, testkill),
+    timer:sleep(100),
+    Pid ! {self(), debug},
+    {ok, S3} = read(),
+    [?_assertMatch({state, _, []}, S1),
+     ?_assertEqual({Ref, ok}, M1),
+     ?_assertMatch({state, _, [{_,ClientPid}]}, S2),
+     ?_assertEqual(S1, S3)].
+
+add(Pid) ->
+    Ref1 = make_ref(),
+    Ref2 = make_ref(),
+    Pid ! {self(), Ref1, {add, "test", "a test event", ?FUTURE_DATE}},
+    {ok, M1} = read(),
+    Pid ! {self(), Ref2, {add, "test", "a test event2", wrong_date}},
+    {ok, M2} = read(),
+    [?_assertEqual({Ref1, ok}, M1),
+     ?_assertEqual({Ref2, {error, bad_timeout}}, M2)].
+
+addremove(Pid) ->
+    Ref1 = make_ref(),
+    Ref2 = make_ref(),
+    Ref3 = make_ref(),
+    %% ask for useless deletion, check the state
+    Pid ! {self(), Ref1, {cancel, "nonexist"}},
+    {ok, M1} = read(),
+    Pid ! {self(), debug},
+    {ok, State1} = read(),
+    %% add an event, check the state
+    Pid ! {self(), Ref2, {add, "test", "a test event", ?FUTURE_DATE}},
+    {ok, M2} = read(),
+    Pid ! {self(), debug},
+    {ok, State2} = read(),
+    %% remove the event, check the state
+    Pid ! {self(), Ref3, {cancel, "test"}},
+    {ok, M3} = read(),
+    Pid ! {self(), debug},
+    {ok, State3} = read(),
+    [?_assertEqual({Ref1, ok}, M1),
+     ?_assertEqual({Ref2, ok}, M2),
+     ?_assertEqual({Ref3, ok}, M3),
+     ?_assertEqual(State1, State3),
+     ?_assert(State2 =/= State3),
+     ?_assertMatch({state,[{"test", {event,"test",_,_,?FUTURE_DATE}}],_}, State2)].
+
+done(Pid) ->
+    Ref = make_ref(),
+    {ok, _} = evserv:subscribe(self()),
+    Pid ! {self(), debug},
+    {ok, S1} = read(),
+    {Date,{H,Min,S}} = calendar:local_time(),
+    DateTime = {Date,{H,Min,S+1}},
+    Pid ! {self(), Ref, {add, "test", "a test event", DateTime}},
+    {ok, M1} = read(),
+    Pid ! {self(), debug},
+    {ok, S2} = read(),
+    X = read(),
+    timer:sleep(750),
+    {ok, M2} = read(),
+    Pid ! {self(), debug},
+    {ok, S3} = read(),
+    [?_assertMatch({state, [], _}, S1),
+     ?_assertEqual({Ref, ok}, M1),
+     ?_assertMatch({state, [{"test",_}], _}, S2),
+     ?_assertEqual(timeout, X),
+     ?_assertEqual({done, "test", "a test event"}, M2),
+     ?_assertEqual(S1,S3)].
+
+interface(_Pid) ->
+    Ref = evserv:subscribe(self()),
+    {Date,{H,Min,S}} = calendar:local_time(),
+    M1 = evserv:add_event("test", "desc", {Date,{H,Min,S+1}}),
+    M2 = evserv:cancel("test"),
+    M3 = evserv:add_event("test1", "desc1", calendar:local_time()),
+    M4 = evserv:add_event2("test2", "desc2", calendar:local_time()),
+    timer:sleep(100),
+    M5 = evserv:listen(2),
+    M6 = evserv:add_event("test3", "desc3", some_atom),
+    M7 = (catch evserv:add_event2("test4", "desc4", some_atom)),
+    [?_assertMatch({ok, _}, Ref),
+     ?_assert(is_reference(element(2, Ref))),
+     ?_assertEqual(ok, M1),
+     ?_assertEqual(ok, M2),
+     ?_assertEqual(ok, M3),
+     ?_assertEqual(ok, M4),
+     ?_assertEqual([{done,"test1","desc1"},{done,"test2","desc2"}], M5),
+     ?_assertEqual({error, bad_timeout}, M6),
+     ?_assertMatch({'EXIT', {bad_timeout,_}}, M7)].
+
+
+%% helpers
+terminate(Pid) -> Pid ! shutdown.
+
+read() ->
+    receive
+        M -> {ok, M}
+    after 500 ->
+        timeout
+    end.
+
diff --git a/learn-you-some-erlang/reminder/src/tests/sup_tests.erl b/learn-you-some-erlang/reminder/src/tests/sup_tests.erl
new file mode 100644
index 0000000..28d7fa9
--- /dev/null
+++ b/learn-you-some-erlang/reminder/src/tests/sup_tests.erl
@@ -0,0 +1,25 @@
+-module(sup_tests).
+-include_lib("eunit/include/eunit.hrl").
+
+restart_test_() ->
+    {"Test that everything restarts until a kill",
+     {setup,
+      fun() -> sup:start(evserv, []) end,
+      fun(_) -> ok end,
+      fun restart/1}}.
+
+restart(_SupPid) ->
+    timer:sleep(100),
+    A = is_pid(whereis(evserv)),
+    catch exit(whereis(evserv), die),
+    timer:sleep(100),
+    B = is_pid(whereis(evserv)),
+    catch exit(whereis(evserv), die),
+    timer:sleep(100),
+    C = is_pid(whereis(evserv)),
+    catch exit(whereis(evserv), shutdown),
+    timer:sleep(500),
+    D = is_pid(whereis(evserv)),
+    ?_assertEqual([true,true,true,false],
+                  [A,B,C,D]).
+