code: def test_transform(self):
      def trans_func(df):
          data1 = {
              "ID": df["ID"].values,
              "price": df["sale_price"].values,
          }
          data2 = {"location": df["location"].values}
          return {"x": data1, "y": data2}
  
      file_path = os.path.join(self.resource_path, "orca/data/csv")
      data_shard = bigdl.orca.data.pandas.read_csv(file_path)
      assert data_shard.is_cached(), "data_shard should be cached"
      transformed_data_shard = data_shard.transform_shard(trans_func)
      assert not data_shard.is_cached(), "data_shard should be uncached"
      assert (
          transformed_data_shard.is_cached()
      ), "transformed_data_shard should be cached"
      data = data_shard.collect()
      assert len(data) == 2, "number of shard should be 2"
      df = data[0]
      assert "location" in df.columns, "location is not in columns"
      trans_data = transformed_data_shard.collect()
      assert len(trans_data) == 2, "number of shard should be 2"
      trans_dict = trans_data[0]
      assert "x" in trans_dict, "x is not in the dictionary"
  
imports: import os.path
  import pytest
  from unittest import TestCase
  import bigdl.orca.data
  import bigdl.orca.data.pandas
  from bigdl.orca.data import SharedValue
  from bigdl.dllib.nncontext import *
  from bigdl.orca.data.transformer import *
  from bigdl.orca import init_orca_context
label_desc: Use image node_id 8 for calling the TestSparkXShards obj's underlying member method code with example usage: obj.test_transform() and returns: dict