import pytest
import os, sys
from creader import ClusterFileReader
from fixtures import data_path

def test_references_on_read(data_path):
    fname= (data_path/'beam_En700eV_-40deg_300V_10us_d0_f0_100.clust').as_posix()
    r = ClusterFileReader(fname)
    clusters = r.read(10)
    assert sys.getrefcount(clusters) == 2 #Over counts by one due to call by reference