code: def test_no_predict():
      # Test that if you try to do this with a model that doesn't have a `predict`
      # method, you get something reasonable.
      class NoPredictModel(base.ReconstModel):
          def __init__(self, gtab):
              base.ReconstModel.__init__(self, gtab)
  
          def fit(self, data, mask=None):
              return NoPredictFit(self, data, mask=mask)
  
      class NoPredictFit(base.ReconstFit):
          def __init__(self, model, data, mask=None):
              base.ReconstFit.__init__(self, model, data)
  
      gtab = gt.gradient_table(fbval, fbvec)
      my_model = NoPredictModel(gtab)
      data = load_nifti_data(fdata)[1:3, 1:3, 1:3]  # Whatever
  
      npt.assert_raises(ValueError, xval.kfold_xval, my_model, data, 2)
  
file_path: dipy/dipy/reconst/tests/test_cross_validation.py
imports: import warnings
  import numpy
  import numpy.testing
  import dipy.reconst.cross_validation
  import dipy.data
  import dipy.reconst.dti
  import dipy.core.gradients
  import dipy.sims.voxel
  import dipy.reconst.csdeconv
  import dipy.reconst.base
  from dipy.io.image import load_nifti_data
  from dipy.reconst.shm import descoteaux07_legacy_msg
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 4 for calling a global function with example usage: test_no_predict() and returns: NoPredictFit