背景：gen_fsm 是Erlang的有限状态机behavior，很实用。爱立信的一位TDD大神写了一篇怎样測试gen_fsm，这个fsm是一个交易系统，负责简单的交易员登陆，插入item，删除item等等，翻译例如以下：
1. Start and Stop
先看下最初版本号的tradepost_tests：
-module(tradepost_tests).
-include_lib("eunit/include/eunit.hrl").
% This is the main point of "entry" for my EUnit testing.
% A generator which forces setup and cleanup for each test in the testset
main_test_() ->
{foreach,
fun setup/0,
fun cleanup/1,
% Note that this must be a List of TestSet or Instantiator
% (I have instantiators == functions generating tests)
[
% First Iteration
fun started_properly/1,
]}.
% Setup and Cleanup
setup() -> {ok,Pid} = tradepost:start_link(), Pid.
cleanup(Pid) -> tradepost:stop(Pid).
% Pure tests below
% ------------------------------------------------------------------------------
% Let's start simple, I want it to start and check that it is okay.
% I will use the introspective function for this
started_properly(Pid) ->
fun() ->
?assertEqual(pending,tradepost:introspection_statename(Pid)),
?assertEqual([undefined,undefined,undefined,undefined,undefined],
tradepost:introspection_loopdata(Pid))
end.
译者注：在eunit中。 setup返回的值作为全部函数包含cleanup的输入，这里是Pid。
started_properly函数是assert 初始为pending, State的值全为空。
如今Test 还不能run。由于tradepost:introspection_statename(Pid) 和 tradepost:introspection_loopdata(Pid)这两个函数还没有。
于是在tradepost.erl里增加：
introspection_statename(TradePost) ->
gen_fsm:sync_send_all_state_event(TradePost,which_statename).
introspection_loopdata(TradePost) ->
gen_fsm:sync_send_all_state_event(TradePost,which_loopdata).
stop(Pid) -> gen_fsm:sync_send_all_state_event(Pid,stop).
handle_sync_event(which_statename, _From, StateName, LoopData) ->
{reply, StateName, StateName, LoopData};
handle_sync_event(which_loopdata, _From, StateName, LoopData) ->
{reply,tl(tuple_to_list(LoopData)),StateName,LoopData};
handle_sync_event(stop,_From,_StateName,LoopData) ->
{stop,normal,ok,LoopData}.这样就能够run test 了
zen:EUnitFSM zenon$ erl -pa ebin/
Erlang R13B04 (erts-5.7.5) [source] [64-bit] [smp:4:4] [rq:4]
[async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.7.5 (abort with ^G)
1> eunit:test(tradepost,[verbose]).
======================== EUnit ========================
module 'tradepost'
module 'tradepost_tests'
tradepost_tests: started_properly...ok
[done in 0.004 s]
[done in 0.005 s]
=======================================================
Test passed.
ok
2>2. 增加測试用例（identify_seller。 insert_item。 withdraw_item）
identify_seller seller是登陆函数。 insert_item。 withdraw_item是添加。删除item的函数
% This is the main point of "entry" for my EUnit testing.
% A generator which forces setup and cleanup for each test in the testset
main_test_() ->
{foreach,
fun setup/0,
fun cleanup/1,
% Note that this must be a List of TestSet or Instantiator
% (I have instantiators)
[
% First Iteration
fun started_properly/1,
% Second Iteration
fun identify_seller/1,
fun insert_item/1,
fun withdraw_item/1
]}.
% Now, we are adding the Seller API tests
identify_seller(Pid) ->
fun() ->
% From Pending, identify seller, then state should be pending
% loopdata should now contain seller_password
?assertEqual(pending,tradepost:introspection_statename(Pid)),
?assertEqual(ok,tradepost:seller_identify(Pid,seller_password)),
?assertEqual(pending,tradepost:introspection_statename(Pid)),
?
assertEqual([undefined,undefined,seller_password,undefined,
undefined],tradepost:introspection_loopdata(Pid))
end.
insert_item(Pid) ->
fun() ->
% From pending and identified seller, insert item
% state should now be item_received, loopdata should now contain itm
tradepost:introspection_statename(Pid),
tradepost:seller_identify(Pid,seller_password),
?assertEqual(ok,tradepost:seller_insertitem(Pid,playstation,
seller_password)),
?assertEqual(item_received,tradepost:introspection_statename(Pid)),
?assertEqual([playstation,undefined,seller_password,undefined,
undefined],tradepost:introspection_loopdata(Pid))
end.
withdraw_item(Pid) ->
fun() ->
% identified seller and inserted item, withdraw item
% state should now be pending, loopdata should now contain only password
tradepost:seller_identify(Pid,seller_password),
tradepost:seller_insertitem(Pid,playstation,seller_password),
?assertEqual(ok,tradepost:withdraw_item(Pid,seller_password)),
?assertEqual(pending,tradepost:introspection_statename(Pid)),
?assertEqual([undefined,undefined,seller_password,undefined,
undefined],tradepost:introspection_loopdata(Pid))
end.
在tradepost.erl添加对应的函数：
%%-------------------------------------------------------------------
%%% @author Gianfranco <zenon@zen.home>
%%% @copyright (C) 2010, Gianfranco
%%% Created : 2 Sep 2010 by Gianfranco <zenon@zen.home>
%%%-------------------------------------------------------------------
-module(tradepost).
-behaviour(gen_fsm).
%% API
-export([start_link/0,introspection_statename/1,introspection_loopdata/1,
stop/1,seller_identify/2,seller_insertitem/3,withdraw_item/2]).
%% States
-export([pending/2,pending/3,item_received/3]).
%% gen_fsm callbacks
-export([init/1, handle_event/3, handle_sync_event/4, handle_info/3,
terminate/3, code_change/4]).
-record(state, {object,cash,seller,buyer,time}).
%%% API
start_link() -> gen_fsm:start_link(?MODULE, [], []).
introspection_statename(TradePost) ->
gen_fsm:sync_send_all_state_event(TradePost,which_statename).
introspection_loopdata(TradePost) ->
gen_fsm:sync_send_all_state_event(TradePost,which_loopdata).
stop(Pid) -> gen_fsm:sync_send_all_state_event(Pid,stop).
seller_identify(TradePost,Password) ->
gen_fsm:sync_send_event(TradePost,{identify_seller,Password}).
seller_insertitem(TradePost,Item,Password) ->
gen_fsm:sync_send_event(TradePost,{insert,Item,Password}).
withdraw_item(TradePost,Password) ->
gen_fsm:sync_send_event(TradePost,{withdraw,Password}).
%%--------------------------------------------------------------------
pending(_Event,LoopData) -> {next_state,pending,LoopData}.
pending({identify_seller,Password},_Frm,LoopD = #state{seller=Password}) ->
{reply,ok,pending,LoopD};
pending({identify_seller,Password},_Frm,LoopD = #state{seller=undefined}) ->
{reply,ok,pending,LoopD#state{seller=Password}};
pending({identify_seller,_},_,LoopD) ->
{reply,error,pending,LoopD};
pending({insert,Item,Password},_Frm,LoopD = #state{seller=Password}) ->
{reply,ok,item_received,LoopD#state{object=Item}};
pending({insert,_,_},_Frm,LoopD) ->
{reply,error,pending,LoopD}.
item_received({withdraw,Password},_Frm,LoopD = #state{seller=Password}) ->
{reply,ok,pending,LoopD#state{object=undefined}};
item_received({withdraw,_},_Frm,LoopD) ->
{reply,error,item_received,LoopD}.
%%--------------------------------------------------------------------
handle_sync_event(which_statename, _From, StateName, LoopData) ->
{reply, StateName, StateName, LoopData};
handle_sync_event(which_loopdata, _From, StateName, LoopData) ->
{reply,tl(tuple_to_list(LoopData)),StateName,LoopData};
handle_sync_event(stop,_From,_StateName,LoopData) ->
{stop,normal,ok,LoopData};
handle_sync_event(_E,_From,StateName,LoopData) ->
{reply,ok,StateName,LoopData}.
%%--------------------------------------------------------------------
init([]) -> {ok, pending, #state{}}.
handle_event(_Event, StateName, State) ->{next_state, StateName, State}.
handle_info(_Info, StateName, State) -> {next_state, StateName, State}.
terminate(_Reason, _StateName, _State) -> ok.
code_change(_OldVsn, StateName, State, _Extra) -> {ok, StateName, State}.再run tests:
zen:EUnitFSM zenon$ erlc -o ebin/ src/*.erl test/*.erl
zen:EUnitFSM zenon$ erl -pa ebin/ -eval 'eunit:test(tradepost,[verbose]).'
Erlang R13B04 (erts-5.7.5) [source] [64-bit] [smp:4:4] [rq:4]
[async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.7.5 (abort with ^G)
1> ======================== EUnit ========================
module 'tradepost'
module 'tradepost_tests'
tradepost_tests: started_properly...ok
tradepost_tests: identify_seller...ok
tradepost_tests: insert_item...ok
tradepost_tests: withdraw_item...ok
[done in 0.015 s]
[done in 0.015 s]
=======================================================
All 4 tests passed.
1>3. 使用eunit_fsm
eunit_fsm是作者写的一个module，使gen_fsm的測试看起来更美观：
原来版本号：
started_properly(Pid) ->
fun() ->
?assertEqual(pending,tradepost:introspection_statename(Pid)),
?
assertEqual([undefined,undefined,undefined,undefined,undefined],
tradepost:introspection_loopdata(Pid))
end.
started_properly(Pid) ->
{"Proper startup test",
[{statename,is,pending},
{loopdata,is,[undefined,undefined,undefined,undefined,undefined]}
]}.再看insert_item, 原来版本号：
insert_item(Pid) ->
fun() ->
% From pending and identified seller, insert item
% state should now be item_received, loopdata should now contain itm
tradepost:introspection_statename(Pid),
tradepost:seller_identify(Pid,seller_password),
?assertEqual(ok,tradepost:seller_insertitem(Pid,playstation,
seller_password)),
?assertEqual(item_received,tradepost:introspection_statename(Pid)),
?assertEqual([playstation,undefined,seller_password,undefined,
undefined],tradepost:introspection_loopdata(Pid))
end.
新版本号：
insert_item(Pid) ->
{"Insert Item Test",
[{state,is,pending},
{call,tradepost,seller_identify,[Pid,seller_password],ok},
{call,tradepost,seller_insertitem,[Pid,playstation,seller_password]},
{state,is,item_received},
{loopdata,is,[playstation,undefined,seller_password,undefined,undefined]}
]}.看起来更易读了吧！
来看下整个的tradepost_test.erl
-module(tradepost_tests).
-include_lib("eunit/include/eunit.hrl").
-include("include/eunit_fsm.hrl").
% This is the main point of "entry" for my EUnit testing.
% A generator which forces setup and cleanup for each test in the testset
main_test_() ->
{foreach,
fun setup/0,
fun cleanup/1,
% Note that this must be a List of TestSet or Instantiator
[
% First Iteration
fun started_properly/1,
% Second Iteration
fun identify_seller/1,
fun insert_item/1,
fun withdraw_item/1
]}.
% Setup and Cleanup
setup() -> {ok,Pid} = tradepost:start_link(), Pid.
cleanup(Pid) -> tradepost:stop(Pid).
% Pure tests below
% ------------------------------------------------------------------------------
% Let's start simple, I want it to start and check that it is okay.
% I will use the introspective function for this
started_properly(Pid) ->
?fsm_test(tradepost,Pid,"Started Properly Test",
[{state,is,pending},
{loopdata,is,[undefined,undefined,undefined,undefined,undefined]}
]).
% Now, we are adding the Seller API tests
identify_seller(Pid) ->
?fsm_test(Pid,"Identify Seller Test",
[{state,is,pending},
{call,tradepost,seller_identify,[Pid,seller_password],ok},
{state,is,pending},
{loopdata,is,[undefined,undefined,seller_password,undefined,undefined]}
]).
insert_item(Pid) ->
?fsm_test(Pid,"Insert Item Test",
[{state,is,pending},
{call,tradepost,seller_identify,[Pid,seller_password],ok},
{call,tradepost,seller_insertitem,[Pid,playstation,seller_password],ok},
{state,is,item_received},
{loopdata,is,[playstation,undefined,seller_password,undefined,undefined]}
]).
withdraw_item(Pid) ->
?fsm_test(Pid,"Withdraw Item Test",
[{state,is,pending},
{call,tradepost,seller_identify,[Pid,seller_password],ok},
{call,tradepost,seller_insertitem,[Pid,button,seller_password],ok},
{state,is,item_received},
{call,tradepost,seller_withdraw_item,[Pid,seller_password],ok},
{state,is,pending},
{loopdata,is,[undefined,undefined,seller_password,undefined,undefined]}
]).
在这里我们看下作者自己写的 eunit_fsm.hrl 和 eunit_fsm.erl
eunit_fsm.hrl :
-define(fsm_test(Id,Title,CmdList),
{Title,fun() -> [ eunit_fsm:translateCmd(Id,Cmd) || Cmd <- CmdList] end}).eunit_fsm.erl:
-module(eunit_fsm).
-export([translateCmd/2,get/2]).
-define(Expr(X),??X).
translateCmd(Id,{state,is,X}) ->
case get(Id,"StateName") of
X -> true;
_V -> .erlang:error({statename_match_failed,
[{module, ?MODULE},
{line, ?LINE},
{expected, X},
{value, _V}]})
end;
translateCmd(_Id,{call,M,F,A,X}) ->
case apply(M,F,A) of
X -> ok;
_V -> .erlang:error({function_call_match_failed,
[{module, ?MODULE},
{line, ?LINE},
{expression, ?Expr(apply(M,F,A))},
{expected, X},
{value, _V}]})
end;
translateCmd(Id,{loopdata,is,X}) ->
case tl(tuple_to_list(get(Id,"StateData"))) of
X -> true;
_V -> .erlang:error({loopdata_match_failed,
[{module, ?MODULE},
{line, ?LINE},
{expected, X},
{value, _V}]})
end.
% StateName or StateData
get(Id,Which) ->
{status,_Pid,_ModTpl, List} = sys:get_status(Id),
AllData = lists:flatten([ X || {data,X} <- lists:last(List) ]),
proplists:get_value(Which,AllData).
看下如今的文件夹结构：
zen:EUnitFSM zenon$ tree .
.
├── ebin
├── include
│ └── eunit_fsm.hrl
├── src
│ └── tradepost.erl
└── test
├── eunit_fsm.erl
└── tradepost_tests.erl
4 directories, 4 files来编译后Run一下：
zen:EUnitFSM zenon$ erlc -o ebin/ src/*.erl test/*.erl
zen:EUnitFSM zenon$ erl -pa ebin/ -eval 'eunit:test(tradepost,[verbose]).'
Erlang R13B04 (erts-5.7.5) [source] [64-bit] [smp:4:4] [rq:4]
[async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.7.5 (abort with ^G)
1> ======================== EUnit ========================
module 'tradepost'
module 'tradepost_tests'
tradepost_tests: started_properly (Started Properly Test)...[0.001 s] ok
tradepost_tests: identify_seller (Identify Seller Test)...ok
tradepost_tests: insert_item (Insert Item Test)...ok
tradepost_tests: withdraw_item (Withdraw Item Test)...ok
[done in 0.014 s]
[done in 0.014 s]
=======================================================
All 4 tests passed.
1>全Pass。