estub aims to add stubbing and mocking to the eunit test framework.

It is still under construction, but when finished you should be able to write tests like this:

 -module(my_module).
 -export([my_fun/0, my_other_fun/1]).

 my_fun() -> my_fun.
 my_fun(Arg) -> Arg.

 estub_test() ->
    ?assertMatch(my_fun, my_module:my_fun()), % real fun returns atom 'my_fun'
    ?stub(_Fun = fun my_module:my_fun/0, _Return = stubbed_value), % fun my_fun should from now on return 'stubbed_value' 
    ?assertCalled(_Fun = fun my_module:my_fun/0, _Times = once), % assert that fun is called once
    ?assertMatch(stubbed_value, my_module:my_fun()),
    ?assertMatch(arg, my_module:my_fun(arg)),
    ?stub(_Fun = fun my_module:my_other_fun/1, _Return = fun(_Arg) -> stubbed_value_1 end), % return not fixed value, but eval fun
    ?assertCalled(_Fun = fun my_module:my_other_fun/1, _Times = twice),
    ?assertMatch(stubbed_value_1, my_module:my_other_fun(1)),
    my_module:my_other_fun(1).