code: def testInvalidWeightsAndReference(self):
      with self.assertRaisesRegex(
          ValueError, "at least two objectives"
      ):
          multi_objective_scalarizer.ChebyshevScalarizer([], [])
      with self.assertRaisesRegex(
          ValueError, "at least two objectives"
      ):
          multi_objective_scalarizer.ChebyshevScalarizer([1], [1])
      with self.assertRaisesRegex(
          ValueError, "weights has 2 elements but"
      ):
          multi_objective_scalarizer.ChebyshevScalarizer(
              [1, 2], [0, 0, 0]
          )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import copy
  import tensorflow.compat.v2
  from tf_agents.bandits.multi_objective import multi_objective_scalarizer
label_desc: Use image node_id 2 for calling the ChebyShevScalarizerTest obj's underlying member method code with example usage: obj.testInvalidWeightsAndReference() without return types