test: added tests for clear

src/arraylist.c

@@ -64,9 +64,6 @@ ArrayListErr arraylist_clear(ArrayList *arr) {
         return ARRLIST_NULL_ARG;
     }
 
-    memset(arr->buffer, 0, arr->capacity * arr->elem_size);
-    arr->capacity = 0;
-    arr->elem_size = 0;
     arr->len = 0;
     return ARRLIST_OK;
 }