code: def test_validates_step_shape(self):
      output = mock.create_autospec(output_lib.Output)
      w = writer_lib.Writer(output)
      with self.assertRaisesRegex(ValueError, "scalar.*step"):
          w.add_scalar("foo", 42.0, np.int64([12]))
  
imports: import time
  from unittest import mock
  import numpy
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.summary import _output
  from tensorboard.summary import _writer
  from tensorboard.summary import _test_util
  from tensorboard.util import tensor_util
  from tensorboard import test
label_desc: Use image node_id 5 for calling the WriterAddScalarTest obj's underlying member method code with example usage: obj.test_validates_step_shape() without return types