message: Add test case for GitHub issue 30750
diff: @@ -125,6 +125,16 @@ class SparseOpsTest(test_util.TensorFlowTestCase, parameterized.TestCase):
  epsilon = 1e-4
  self.assertLess(gradient_checker.max_error(*grads), epsilon)
  + def testSparseTensorToDenseString(self):
  + sp = sparse_tensor.SparseTensor(
  + indices=[[0, 0], [1, 2]],
  + values=['a', 'b'],
  + dense_shape=[2, 3])
  + dense = sparse_ops.sparse_tensor_to_dense(sp)
  + expected_dense = [['a', '', ''], ['', '', 'b']]
  + result_dense = self.evaluate(dense)
  + self.assertAllEqual(expected_dense, result_dense)
  +
  if __name__ == '__main__':
  googletest.main()
  