code: def testInvalidPos(self):
      # Test case for GitHub issue 46900.
      with self.assertRaises(
          (ValueError, errors_impl.InvalidArgumentError)
      ):
          x = string_ops.substr(b"abc", len=1, pos=[1, -1])
          self.evaluate(x)
  
      with self.assertRaises(
          (ValueError, errors_impl.InvalidArgumentError)
      ):
          x = string_ops.substr(b"abc", len=1, pos=[1, 2])
          self.evaluate(x)
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 15 for calling the SubstrOpTest obj's underlying member method code with example usage: obj.testInvalidPos() without return types