text: import pickle
  
  from django.forms import BooleanField, ValidationError
  from django.test import SimpleTestCase
  
  
  class BooleanFieldTest(SimpleTestCase):
  
      def test_booleanfield_clean_1(self):
          f = BooleanField()
          with self.assertRaisesMessage(ValidationError, "'This field is required.'"):
              f.clean('')
          with self.assertRaisesMessage(ValidationError, "'This field is required.'"):
              f.clean(None)
          self.assertTrue(f.clean(True))
          with self.assertRaisesMessage(ValidationError, "'This field is required.'"):
              f.clean(False)
          self.assertTrue(f.clean(1))
          with self.assertRaisesMessage(ValidationError, "'This field is required.'"):
              f.clean(0)
          self.assertTrue(f.clean('Django rocks'))
          self.assertTrue(f.clean('True'))
          with self.assertRaisesMessage(ValidationError, "'This field is required.'"):
              f.clean('False')
  
      def test_booleanfield_clean_2(self):
          f = BooleanField(required=False)
          self.assertIs(f.clean(''), False)
          self.assertIs(f.clean(None), False)
          self.assertIs(f.clean(True), True)
          self.assertIs(f.clean(False), False)
          self.assertIs(f.clean(1), True)
          self.assertIs(f.clean(0), False)
          self.assertIs(f.clean('1'), True)
          self.assertIs(f.clean('0'), False)
          self.assertIs(f.clean('Django rocks'), True)
          self.assertIs(f.clean('False'), False)
          self.assertIs(f.clean('false'), False)
          self.assertIs(f.clean('FaLsE'), False)
  
      def test_boolean_picklable(self):
          self.assertIsInstance(pickle.loads(pickle.dumps(BooleanField())), BooleanField)
  
      def test_booleanfield_changed(self):
          f = BooleanField()
          self.assertFalse(f.has_changed(None, None))
          self.assertFalse(f.has_changed(None, ''))
          self.assertFalse(f.has_changed('', None))
          self.assertFalse(f.has_changed('', ''))
          self.assertTrue(f.has_changed(False, 'on'))
          self.assertFalse(f.has_changed(True, 'on'))
          self.assertTrue(f.has_changed(True, ''))
          # Initial value may have mutated to a string due to show_hidden_initial (#19537)
          self.assertTrue(f.has_changed('False', 'on'))
          # HiddenInput widget sends string values for boolean but doesn't clean them in value_from_datadict
          self.assertFalse(f.has_changed(False, 'False'))
          self.assertFalse(f.has_changed(True, 'True'))
          self.assertTrue(f.has_changed(False, 'True'))
          self.assertTrue(f.has_changed(True, 'False'))
  