A rather convoluted mechanism for getting subsequent calls to a mecked function to return different results.

multiple_expect_results.erl

-module(multiple_expect_results).

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

multiple_results_test() ->
    ok = meck:new(some_mod),
    meck:expect(some_mod, get_pid, fun() -> self() end),
    meck:expect(some_mod, some_fun,
                fun() ->
                        receive
                            {{some_mod, some_fun}, Result} ->
                                Result
                        end
                end),
    ModPid = some_mod:get_pid(),
    ModPid ! {{some_mod, some_fun}, a},
    ModPid ! {{some_mod, some_fun}, b},
    ModPid ! {{some_mod, some_fun}, c},

    ?assertEqual(a, some_mod:some_fun()),
    ?assertEqual(b, some_mod:some_fun()),
    ?assertEqual(c, some_mod:some_fun()).