code: def test_to_dense(self, backend_config):
      xp = backend_config.xp
  
      data = xp.array([3.0, 0.0, 4.0, -5.0], dtype=xp.float32)
      row = xp.array([0, 0, 1, 0])
      col = xp.array([0, 1, 2, 0])
  
      if self.nbatch == 1:
          data = data[xp.newaxis]
          row = row[xp.newaxis]
          col = col[xp.newaxis]
  
      x0 = xp.array(
          [[-2.0, 0.0, 0.0], [0.0, 0.0, 4.0]], dtype=xp.float32
      )
      if self.nbatch == 1:
          x0 = x0[xp.newaxis]
      x1 = utils.CooMatrix(data, row, col, (2, 3)).to_dense()
      xp.testing.assert_array_equal(x0, x1)
  
file_path: chainer/tests/chainer_tests/utils_tests/test_sparse.py
imports: import unittest
  import numpy
  from chainer import testing
  from chainer import utils
label_desc: Use image node_id 1 for calling the TestCooMatrixDuplicateIndices obj's underlying member method code with example usage: obj.test_to_dense(backend_config) without return types