code: def test_default_boston_sparse(self):
      if self.__class__ == BaseRegressionComponentTest:
          return
  
      if SPARSE not in self.module.get_properties()["input"]:
          return
  
      for i in range(2):
          with ignore_warnings(regressor_warnings):
              predictions, targets, _ = _test_regressor(
                  dataset="boston", Regressor=self.module, sparse=True
              )
  
          self.assertAlmostEqual(
              self.res["default_boston_sparse"],
              sklearn.metrics.r2_score(targets, predictions),
              places=self.res.get("default_boston_sparse_places", 7),
          )
  
imports: from typing import Container, Type
  import numpy
  import sklearn.metrics
  from autosklearn.pipeline.components.regression import RegressorChoice, _regressors
  from autosklearn.pipeline.components.regression.libsvm_svr import LibSVM_SVR
  from autosklearn.pipeline.constants import SPARSE
  from autosklearn.pipeline.util import _test_regressor, _test_regressor_iterative_fit
  import pytest
  import unittest
  from test.test_pipeline.ignored_warnings import ignore_warnings, regressor_warnings
label_desc: Use image node_id 4 for calling the BaseRegressionComponentTest obj's underlying member method code with example usage: obj.test_default_boston_sparse() without return types