old_contents: import unittest
  import os
  from test.util import ykman_cli
  
  
  @unittest.skipIf(
      os.environ.get('DESTRUCTIVE_TEST_YUBIKEY_SERIAL') is None,
      'DESTRUCTIVE_TEST_YUBIKEY_SERIAL == None')
  class TestExternalLibraries(unittest.TestCase):
  
      def test_ykman_version(self):
          output = ykman_cli('-v')
          # Test that major version is 1 on all libs
          self.assertIn('libykpers 1', output)
          self.assertIn('libusb 1', output)
  
      def test_ykman_version_not_found(self):
          output = ykman_cli('-v')
          self.assertNotIn('not found!', output)
          self.assertNotIn('<pyusb backend missing>', output)
  
new_contents: import unittest
  from test.util import ykman_cli
  
  
  class TestExternalLibraries(unittest.TestCase):
  
      def test_ykman_version(self):
          output = ykman_cli('-v')
          # Test that major version is 1 on all libs
          self.assertIn('libykpers 1', output)
          self.assertIn('libusb 1', output)
  
      def test_ykman_version_not_found(self):
          output = ykman_cli('-v')
          self.assertNotIn('not found!', output)
          self.assertNotIn('<pyusb backend missing>', output)
  
subject: Remove unnecessary @skipIf from test_external_libs