old_contents: import sublime
  from unittest import TestCase
  
  version = sublime.version()
  
  class TestDiffListener(TestCase):
  
      def setUp(self):
          self.view = sublime.active_window().new_file()
  
      def tearDown(self):
          if self.view:
              self.view.set_scratch(True)
              self.view.window().run_command("close_file")
  
      def TestOnModified(self):
          # put actual tests here
          pass
  
new_contents: import sublime
  from unittest import TestCase
  
  version = sublime.version()
  
  class TestDiffListener(TestCase):
  
      def setUp(self):
          self.view = sublime.active_window().new_file()
  
      def tearDown(self):
          if self.view:
              self.view.set_scratch(True)
              self.view.window().run_command("close_file")
  
      def testOnModify(self):
          # put actual test here
          pass
  
      def testOnClose(self):
          # insert test here
          pass
subject: add additional test stubs