code: def test_astype(self):
      self.assert_eq(self.pser.astype(str), self.psser.astype(str))
  
imports: import decimal
  import datetime
  import pandas
  from pyspark import pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase
  from pyspark.pandas.tests.data_type_ops.testing_utils import OpsTestBase
label_desc: Use image node_id 34 for calling the ComplexOpsTestsMixin obj's underlying member method code with example usage: obj.test_astype() without return types