text: # --------------------------------------------------------
  # (c) Copyright 2014, 2020 by Jason DeLaat.
  # Licensed under BSD 3-clause licence.
  # --------------------------------------------------------
  import unittest
  
  import pymonad.monoid as monoid
  
  class MZero_Tests(unittest.TestCase):
      def test_class_and_object_are_the_same(self):
          self.assertEqual(monoid.ZERO, monoid.ZERO())
  
      def test_left_identity(self):
          self.assertEqual(monoid.ZERO + 10, 10)
  
      def test_right_identity(self):
          self.assertEqual(10 + monoid.ZERO, 10)
  
      def test_repr(self):
          self.assertEqual(str(monoid.ZERO), 'MZERO')
  