code: def test__check_classifier_input():
      """Test for valid estimator format.
  
      1. Test correct: X: np.array of 2 and 3 dimensions vs y:np.array and np.Series
      2. Test correct: X: pd.DataFrame with 1 and 3 cols vs y:np.array and np.Series
      3. Test incorrect: X with fewer cases than y
      4. Test incorrect: y as a list
      5. Test incorrect: too few cases or too short a series
      """
      clf = _DummyClassifier()
  
      def _check_classifier_input(X, y=None, enforce_min_instances=1):
          return clf._check_input(X, y, enforce_min_instances)
  
      # 1. Test correct: X: np.array of 2 and 3 dimensions vs y:np.array and np.Series
      test_X1 = np.random.uniform(-1, 1, size=(5, 10))
      test_X2 = np.random.uniform(-1, 1, size=(5, 2, 10))
      test_y1 = np.random.randint(0, 1, size=5)
      test_y2 = pd.Series(np.random.randn(5))
      _check_classifier_input(test_X2)
      _check_classifier_input(test_X2, test_y1)
      _check_classifier_input(test_X2, test_y2)
      # 2. Test correct: X: pd.DataFrame with 1 (univariate) and 3 cols(multivariate) vs
      # y:np.array and np.Series
      test_X3 = _create_nested_dataframe(5, 1, 10)
      test_X4 = _create_nested_dataframe(5, 3, 10)
      _check_classifier_input(test_X3, test_y1)
      _check_classifier_input(test_X4, test_y1)
      _check_classifier_input(test_X3, test_y2)
      _check_classifier_input(test_X4, test_y2)
      # 3. Test incorrect: X with fewer cases than y
      test_X5 = np.random.uniform(-1, 1, size=(3, 4, 10))
      with pytest.raises(
          ValueError, match=r".*Mismatch in number of cases*."
      ):
          _check_classifier_input(test_X5, test_y1)
      # 4. Test incorrect data type: y is a List
      test_y3 = [1, 2, 3, 4, 5]
      with pytest.raises(
          TypeError, match="must be in an sktime compatible format"
      ):
          _check_classifier_input(test_X1, test_y3)
      # 5. Test incorrect: too few cases or too short a series
      with pytest.raises(
          ValueError, match=r".*Minimum number of cases required*."
      ):
          _check_classifier_input(
              test_X2, test_y1, enforce_min_instances=6
          )
  
imports: import pickle
  import numpy
  import pandas
  import pytest
  from sklearn.model_selection import KFold
  from sktime.classification.base import BaseClassifier
  from sktime.classification.deep_learning.base import BaseDeepClassifier
  from sktime.classification.distance_based import KNeighborsTimeSeriesClassifier
  from sktime.classification.dummy import DummyClassifier
  from sktime.utils._testing.estimator_checks import _assert_array_almost_equal
  from sktime.utils._testing.panel import _make_classification_y, _make_panel, make_classification_problem
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 4 for calling a global function with example usage: test__check_classifier_input() and returns: clf