gen_server mocking. This project is functioning but still young.

     {ok, Mock} = gen_server_mock:new(),

     gen_server_mock:expect_call(Mock, fun(one,  _From, _State)            -> ok end),
     gen_server_mock:expect_call(Mock, fun(two,  _From,  State)            -> {ok, State} end),
     gen_server_mock:expect_call(Mock, fun(three, _From,  State)           -> {ok, good, State} end),
     gen_server_mock:expect_call(Mock, fun({echo, Response}, _From, State) -> {ok, Response, State} end),
     gen_server_mock:expect_cast(Mock, fun(fish, State) -> {ok, State} end),
     gen_server_mock:expect_info(Mock, fun(cat,  State) -> {ok, State} end),
     
     ok = gen_server:call(Mock, one),
     ok = gen_server:call(Mock, two),
     good = gen_server:call(Mock, three),
     tree = gen_server:call(Mock, {echo, tree}),
     ok   = gen_server:cast(Mock, fish),
     Mock ! cat,
     
     gen_server_mock:assert_expectations(Mock),
     {ok}.

See test/src/eunit_gen_server_mock.erl

Currently three expectations are supported: expect_call, expect_cast, expect_info.

The fun argument takes the same arguments as the respective handle_ gen_server call. However, unlike the handle_ calls, the response should be one of ok, {ok, NewState}, {ok, Response, NewState}. Anything else will be considered a failure.

For example:

• expect_call(Mock, fun(Request, From, State) -> ok end)
• expect_cast(Mock, fun(Msg, State) -> {ok, State} end)
• expect_info(Mock, fun(Info, State) -> {error, State} end) (will raise an error, return {ok, State} for success)

Alpha. API may change depending on feedback. Hosted on Github - patches readily accepted.

• skelerl, if you want to run tests
• tested with eunit, should work with other libraries in theory

I suspect that one could write a more general process mocking library relatively easily.

• Initial blog post
• Work inspired by this post
• Github Repo (Patches readily accepted)
• Mocks Aren't Stubs

• Nate Murray <nmurray [AT] attinteractive.com> github