text: from unittest import mock
  
  from django.test import TestCase
  from django.core.exceptions import ValidationError
  from django.core.files import File
  
  from MetioTube.core.validators import validate_video_file
  
  
  class ValidateVideoFileTests(TestCase):
      def setUp(self):
          self.file = mock.MagicMock(spec=File)
  
      def test_validateVideoFileWhenExtensionIsInvalid_expectToRaise(self):
          self.file.name = 'test.mkv'
  
          with self.assertRaises(ValidationError) as context:
              validate_video_file(self.file)
  
          self.assertEqual('Wrong video extension! Valid extensions are: mp4, webm, mov!', context.exception.message)
  
      def test_validateVideoFileWhenSizeIsToBig_expectToRaise(self):
          self.file.name = 'test.mp4'
          self.file.size = 104857601
  
          with self.assertRaises(ValidationError) as context:
              validate_video_file(self.file)
  
          self.assertEqual('Max video size is 100MB', context.exception.message)
  
      def test_validateVideoFileWhenIsValid_expectNothing(self):
          self.file.name = 'test.mp4'
          self.file.size = 123
          validate_video_file(self.file)
  