code: def test_X_validation(self):
      dhnet = algorithms.DiscreteHopfieldNetwork()
      dhnet.weight = np.array([[0, 1], [1, 0]])
  
      # Invalid discrete input values
      with self.assertRaises(ValueError):
          dhnet.train(np.array([-1, 1]))
  
      with self.assertRaises(ValueError):
          dhnet.energy(np.array([-1, 1]))
  
      with self.assertRaises(ValueError):
          dhnet.predict(np.array([-1, 1]))
  
file_path: neupy/tests/algorithms/memory/test_discrete_hn.py
imports: import numpy
  from neupy import algorithms
  from algorithms.memory.data import zero, one, two, half_one, half_zero, half_two
  from base import BaseTestCase
label_desc: Use image node_id 3 for calling the DiscreteHopfieldNetworkTestCase obj's underlying member method code with example usage: obj.test_X_validation() without return types