rebar.config

{cover_enabled, true}.

{port_specs, [
              {"priv/hyper_carray.so", ["c_src/hyper_carray.c"]}
             ]}.

{port_env, [
            {"(linux|solaris|freebsd|netbsd|openbsd|dragonfly|darwin|gnu)",
                "CFLAGS", "$CFLAGS -std=c99 -Wall -Werror -O3"},
            {"win32", "CXXFLAGS", "$CXXFLAGS /O2 /DNDEBUG"}
           ]}.