test/pdict_statem.erl

%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% ex: ts=4 sw=4 et
%%
%% This file is part of Triq - Trifork QuickCheck
%%
%% Copyright (c) 2010-2013 by Trifork
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%

-module(pdict_statem).

-export([ initial_state/0
        , key/0
        , command/1
        , precondition/2
        , postcondition/3
        , next_state/3
        ]).

-include("triq.hrl").

%% use eunit
-include_lib("eunit/include/eunit.hrl").

%%
%% A simple statem test for the process dictionary; tests the
%% operations erlang:put/2, erlang:get/1 and and erlang:erase/1.
%%

prop_pdict_statem() ->
    ?FORALL(Cmds,
            triq_statem:commands(pdict_statem),
            begin
                triq_statem:run_commands(pdict_statem, Cmds),
                true
            end).

-define(KEYS, [a,b,c,d]).
key() ->
    oneof(?KEYS).

initial_state() ->
    lists:filter(fun({Key,_}) -> lists:member(Key, ?KEYS) end,
                 erlang:get()).

command([]) ->
    {call, erlang, put, [key(), int()]};
command(Props) ->
    ?LET({Key,Value}, frequency([{5, elements(Props)},
                                 {1, {key(),int()}}]),
         oneof([{call, erlang, put,   [Key, Value]},
                {call, erlang, get,   [Key]},
                {call, erlang, erase, [Key]}
               ])).

precondition(_, {call, erlang, put, [_,_]}) ->
    true;
precondition(Props, {call, erlang, get, [Key]}) ->
    proplists:is_defined(Key,Props);
precondition(Props, {call, erlang, erase, [Key]}) ->
    proplists:is_defined(Key,Props);
precondition(_,_) ->
    false.

postcondition(Props, {call, erlang, put, [Key,_]}, undefined) ->
    not proplists:is_defined(Key,Props);
postcondition(Props, {call, erlang, put, [Key,_]}, Old) ->
    {Key,Old} == proplists:lookup(Key,Props);
postcondition(Props, {call, erlang, get, [Key]}, Val) ->
    {Key,Val} == proplists:lookup(Key,Props);
postcondition(Props, {call, erlang, erase, [Key]}, Val) ->
    {Key,Val} == proplists:lookup(Key,Props);
postcondition(_,_,_) ->
    false.

next_state(Props, _Var, {call, erlang, put, [Key,Value]}) ->
    [{Key,Value}] ++ Props;
next_state(Props, _Var, {call, erlang, erase, [Key]}) ->
    proplists:delete(Key,Props);
next_state(Props, _Var, {call, erlang, get, [_]}) ->
    Props.


%% -------------------------------------------------------------------
%% Property Testing
%% -------------------------------------------------------------------

run_property_testing_test_() ->
    {timeout, 60, fun run_property_testing_case/0}.

run_property_testing_case() ->
    EunitLeader = erlang:group_leader(),
    erlang:group_leader(whereis(user), self()),
    Res = triq:module(?MODULE),
    erlang:group_leader(EunitLeader, self()),
    ?assert(Res).