code: def testInvalidArgsUnknownIndices(self):
      with self.cached_session():
          placeholder = array_ops.placeholder(
              dtypes.int32, name="placeholder"
          )
          reduced = string_ops.reduce_join(
              ["test", "test2"], axis=placeholder
          )
  
          with self.assertRaisesOpError("reduction dimension -2"):
              reduced.eval(feed_dict={placeholder.name: -2})
          with self.assertRaisesOpError("reduction dimension 2"):
              reduced.eval(feed_dict={placeholder.name: 2})
  
imports: import itertools
  import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 16 for calling the ReduceJoinTest obj's underlying member method code with example usage: obj.testInvalidArgsUnknownIndices() without return types