new_contents: #!/usr/bin/env python3
  """
  this module contains test cases (based on Python's unittest)
  """
  
  import unittest
  
  from pieces import (
      ChessPiece,
  )
  
  
  class ChessPieceTest(unittest.TestCase):
      def test_set_pos(self):
          """
          test case for ChessPiece.set_pos and ChessPiece.get_pos methods
          """
          piece = ChessPiece(3, 4)
          self.assertEqual(piece.get_pos(), (3, 4))
  
          piece.set_pos(6, 5)
          self.assertEqual(piece.get_pos(), (6, 5))
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: add tests.py, with test case for ChessPiece: set_pos, and get_pos