code: def test_relations(self):
      resource_path = os.path.join(
          os.path.split(__file__)[0], "../resources"
      )
      path = os.path.join(resource_path, "qa")
      relations = Relations.read(path + "/relations.txt")
      assert isinstance(relations, list)
      relations2 = Relations.read(path + "/relations.csv", self.sc, 2)
      assert isinstance(relations2, RDD)
      relations3 = Relations.read_parquet(
          path + "/relations.parquet", self.sc
      )
      assert isinstance(relations3, RDD)
  
file_path: BigDL/python/dllib/test/bigdl/feature/test_feature_common.py
imports: import pytest
  from bigdl.dllib.nn.layer import *
  from bigdl.dllib.nn.criterion import *
  from bigdl.dllib.optim.optimizer import *
  from test.bigdl.test_zoo_utils import ZooTestCase
  from bigdl.dllib.feature.common import *
  from bigdl.dllib.nncontext import init_nncontext, init_spark_conf
label_desc: Use image node_id 3 for calling the TestFeatureCommon obj's underlying member method code with example usage: obj.test_relations() without return types