new_contents: import unittest
  
  from bfg9000.builtins.version import bfg9000_required_version, bfg9000_version
  from bfg9000.versioning import bfg_version, VersionError
  
  
  class TestRequiredVersion(unittest.TestCase):
      def test_bfg_version(self):
          bfg9000_required_version('>=0.1.0')
          self.assertRaises(VersionError, bfg9000_required_version, '<=0.1.0')
  
      def test_python_version(self):
          bfg9000_required_version(python_version='>=2.7.0')
          self.assertRaises(VersionError, bfg9000_required_version, None,
                            '<=2.0.0')
  
      def test_both_versions(self):
          bfg9000_required_version('>=0.1.0', '>=2.7.0')
          self.assertRaises(VersionError, bfg9000_required_version, '<=0.1.0',
                            '<=2.0.0')
  
  
  class TestVersion(unittest.TestCase):
      def test_version(self):
          self.assertEqual(bfg9000_version(), bfg_version)
  
subject: Add unit tests for versioning builtins