lib/erl/rebar.config

{erl_opts, [{platform_define, "^R.*", otp16_or_less}, debug_info]}.

{profiles, [
    {test, [
        {deps, [meck]},
        {eunit_tests, [
            {dir, "test"},
            {dir, "test/gen-erl"}
        ]}
    ]}
]}.