old_contents: from unittest import TestCase
  
  from mmeter.mmeter import App
  
  
  class TestAppInstance(TestCase):
  
  	def setUp(self):
  		self.app = App()
  
  	def tearDown(self):
  		self.app.destroy()
  
  	def test_instance(self):
  		self.assertIsInstance(self.app, App)
  
  
  if __name__ == '__main__':
  	unittest.main()
  
new_contents: from tkinter import Tk
  from unittest import TestCase
  
  from mmeter.mmeter import App
  
  
  class TestAppInstance(TestCase):
  
  	def setUp(self):
  		self.root = Tk()
  		self.app = App(self.root)
  
  	def tearDown(self):
  		self.app.destroy()
  
  	def test_instance(self):
  		self.assertIsInstance(self.app, App)
  
  
  if __name__ == '__main__':
  	unittest.main()
  
subject: Change test.