code: def test_const_ext(self):
      a = np.array([[1, 2, 3, 4, 5], [9, 8, 7, 6, 5]])
  
      const = const_ext(a, 2, axis=1)
      expected = np.array(
          [[1, 1, 1, 2, 3, 4, 5, 5, 5], [9, 9, 9, 8, 7, 6, 5, 5, 5]]
      )
      assert_array_equal(const, expected)
  
      const = const_ext(a, 1, axis=0)
      expected = np.array(
          [
              [1, 2, 3, 4, 5],
              [1, 2, 3, 4, 5],
              [9, 8, 7, 6, 5],
              [9, 8, 7, 6, 5],
          ]
      )
      assert_array_equal(const, expected)
  
file_path: scipy/scipy/signal/tests/test_array_tools.py
imports: import numpy
  from numpy.testing import assert_array_equal
  from pytest import raises
  from scipy.signal._arraytools import axis_slice, axis_reverse, odd_ext, even_ext, const_ext, zero_ext
label_desc: Use image node_id 5 for calling the TestArrayTools obj's underlying member method code with example usage: obj.test_const_ext() without return types