old_contents: from protobuf3.fields.string import StringField
  from protobuf3.message import Message
  from unittest import TestCase
  
  
  class TestStringField(TestCase):
      def setUp(self):
          class StringTestMessage(Message):
              b = StringField(field_number=2)
  
          self.msg_cls = StringTestMessage
  
      def test_get(self):
          msg = self.msg_cls()
  
          msg.parse_from_bytes([0x12, 0x07, 0x74, 0x65, 0x73, 0x74, 0x69, 0x6E, 0x67])
          self.assertEqual(msg.b, 'testing')
  
      def test_default_get(self):
          msg = self.msg_cls()
  
          self.assertEqual(msg.b, '')
  
      def test_set(self):
          msg = self.msg_cls()
  
          msg.b = 'test'
          self.assertEqual(msg.b, 'test')
  
      def test_invalid_set(self):
          msg = self.msg_cls()
  
          def failure():
              msg.b = 123
  
          self.assertRaises(ValueError, failure)
  
new_contents: from protobuf3.fields.string import StringField
  from protobuf3.message import Message
  from unittest import TestCase
  
  
  class TestStringField(TestCase):
      def setUp(self):
          class StringTestMessage(Message):
              b = StringField(field_number=2)
  
          self.msg_cls = StringTestMessage
  
      def test_get(self):
          msg = self.msg_cls()
  
          msg.parse_from_bytes(bytes([0x12, 0x07, 0x74, 0x65, 0x73, 0x74, 0x69, 0x6E, 0x67]))
          self.assertEqual(msg.b, 'testing')
  
      def test_default_get(self):
          msg = self.msg_cls()
  
          self.assertEqual(msg.b, '')
  
      def test_set(self):
          msg = self.msg_cls()
  
          msg.b = 'test'
          self.assertEqual(msg.b, 'test')
  
      def test_invalid_set(self):
          msg = self.msg_cls()
  
          def failure():
              msg.b = 123
  
          self.assertRaises(ValueError, failure)
  
subject: Update string tests to reflect new behaviour.