code: def test_value_error(self):
      with self.assertRaises(ValueError):
          self.dist(loc=self.params["loc"])
  
imports: import unittest
  import numpy
  from chainer import cuda
  from chainer import distributions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 2 for calling the TestMultivariateNormal obj's underlying member method code with example usage: obj.test_value_error() without return types