code: def test_pad_tt_rank(n_pad):
      """Test for pad_tt_rank"""
      # Testing for a tensor-train
      rank = (1, 2, 2, 2, 1)
      tt = random_tt((4, 3, 5, 2), rank=rank)
      padded_tt = tl.tt_tensor.TTTensor(
          pad_tt_rank(tt, n_padding=n_pad, pad_boundaries=False)
      )
      rec = tt.to_tensor()
      rec_padded = padded_tt.to_tensor()
      assert_array_almost_equal(rec, rec_padded, decimal=4)
      assert_(
          padded_tt.rank == (1, *[i + n_pad for i in rank[1:-1]], 1)
      )
  
      # Testing for a Tensor-Ring
      rank = (2, 3, 4, 5, 2)
      tr = random_tr((4, 3, 5, 2), rank=rank)
      padded_tr = tl.tr_tensor.TRTensor(
          pad_tt_rank(tr, n_padding=n_pad, pad_boundaries=True)
      )
      rec = tr.to_tensor()
      rec_padded = padded_tr.to_tensor()
      assert_array_almost_equal(rec, rec_padded, decimal=4)
      assert_(padded_tr.rank == tuple([i + n_pad for i in rank]))
  
      # Testing for a TT-Matrix
      rank = (1, 2, 3, 1)
      ttm = random_tt_matrix((2, 3, 3, 4, 2, 2), rank=rank)
      padded_ttm = tl.tt_matrix.TTMatrix(
          pad_tt_rank(ttm, n_padding=n_pad, pad_boundaries=False)
      )
      rec = ttm.to_tensor()
      rec_padded = padded_ttm.to_tensor()
      assert_array_almost_equal(rec, rec_padded, decimal=4)
      assert_(
          padded_ttm.rank == (1, *[i + n_pad for i in rank[1:-1]], 1)
      )
  
file_path: tensorly/tensorly/tests/test_tt_tensor.py
imports: import numpy
  import tensorly
  from ..decomposition import tensor_train
  from ..tt_tensor import _validate_tt_tensor, pad_tt_rank
  from ..tt_tensor import validate_tt_rank, _tt_n_param
  from ..testing import assert_array_almost_equal, assert_equal, assert_raises, assert_
  from ..random import random_tt, random_tr, random_tt_matrix
  import pytest
label_desc: Use image node_id 6 for calling a global function with example usage: test_pad_tt_rank(n_pad) without return types