code: def test_to_csv_with_partition_cols(self):
      pdf = pd.DataFrame({"a": [1, 2, 3], "b": ["a", "b", "c"]})
      psdf = ps.DataFrame(pdf)
  
      with self.temp_dir() as dirpath:
          psdf.to_csv(dirpath, partition_cols="b", num_files=1)
  
          partition_paths = [
              path
              for path in os.listdir(dirpath)
              if path.startswith("b=")
          ]
          assert len(partition_paths) > 0
          for partition_path in partition_paths:
              column, value = partition_path.split("=")
              expected = (
                  pdf[pdf[column] == value]
                  .drop("b", axis=1)
                  .to_csv(index=False)
              )
  
              output_paths = [
                  path
                  for path in os.listdir(
                      "%s/%s" % (dirpath, partition_path)
                  )
                  if path.startswith("part-")
              ]
              assert len(output_paths) > 0
              output_path = "%s/%s/%s" % (
                  dirpath,
                  partition_path,
                  output_paths[0],
              )
              with open(output_path) as f:
                  self.assertEqual(f.read(), expected)
  
imports: import os
  from contextlib import contextmanager
  import pandas
  import numpy
  from pyspark import pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase, TestUtils
label_desc: Use image node_id 24 for calling the CsvTestsMixin obj's underlying member method code with example usage: obj.test_to_csv_with_partition_cols() without return types