old_contents: """ Test the cross_val module
  """
  
  import numpy as np
  
  import nose
  
  from .. import cross_val
  
  def test_kfold():
      # Check that errors are raise if there is not enough samples
      nose.tools.assert_raises(AssertionError, cross_val.KFold, 3, 3)
      y = [0, 0, 1, 1, 2]
      nose.tools.assert_raises(AssertionError, cross_val.StratifiedKFold, y, 3)
  
  
new_contents: """ Test the cross_val module
  """
  
  import numpy as np
  
  import nose
  
  from ..base import BaseEstimator
  from .. import cross_val
  
  class MockClassifier(BaseEstimator):
      """Dummy classifier to test the cross-validation
      
      """
      def __init__(self, a=0):
          self.a = a
  
      def fit(self, X, Y, **params):
          self._set_params(**params)
          return self
  
      def predict(self, T):
          return T.shape[0]
  
      def score(self, X=None, Y=None):
          return 1./(1+np.abs(self.a))
  
  
  X = np.ones((10, 2))
  y = np.arange(10)/2
  
  ################################################################################
  # Tests
  
  def test_kfold():
      # Check that errors are raise if there is not enough samples
      nose.tools.assert_raises(AssertionError, cross_val.KFold, 3, 3)
      y = [0, 0, 1, 1, 2]
      nose.tools.assert_raises(AssertionError, cross_val.StratifiedKFold, y, 3)
  
  
  def test_cross_val_score():
      clf = MockClassifier()
      for a in range(-10, 10):
          clf.a = a
          # Smoke test
          score = cross_val.cross_val_score(clf, X, y)
          np.testing.assert_array_equal(score,  clf.score(X, y))
  
  
subject: Add a smoke test for cross_val_score