code: def test_oja_exceptions(self):
      ojanet = algorithms.Oja(
          minimized_data_size=1, step=0.01, verbose=False
      )
  
      with self.assertRaises(NotTrained):
          # Can't reconstruct without training
          ojanet.reconstruct(np.random.random((4, 1)))
  
      with self.assertRaises(NotTrained):
          # Can't predict without training
          ojanet.predict(np.random.random((4, 1)))
  
      ojanet.train(self.data, epochs=2)
  
      with self.assertRaises(ValueError):
          # Invalid #feature for reconstruct
          ojanet.reconstruct(np.random.random((3, 3)))
  
      with self.assertRaises(ValueError):
          # Invalid #feature for train
          ojanet.train(np.random.random((4, 10)))
  
file_path: neupy/tests/algorithms/associative/test_oja.py
imports: import numpy
  from neupy import algorithms, init
  from neupy.exceptions import NotTrained
  from base import BaseTestCase
  from helpers import vectors_for_testing
label_desc: Use image node_id 3 for calling the OjaTestCase obj's underlying member method code with example usage: obj.test_oja_exceptions() without return types