test.c

void test_dll_dll_insert_before_insterts_item_before() {
    t_dll *dll = dll_init();

    dll_append(dll, "test1");
    dll_append(dll, "test3");

    t_dll_element *element = DLL_TAIL(dll);

    dll_insert_before(dll, element, "test2");

    CU_ASSERT_STRING_EQUAL(DLL_NEXT(DLL_HEAD(dll))->data, "test2");
}