text: from django.test import TestCase
  from django.core.files import File
  
  from thumbnails.post_processors import optimize
  
  
  class PostProcessorsTest(TestCase):
  
      def test_optimize(self):
          with open('thumbnails/tests/tests.png', 'rb') as image_file:
              original_file = File(image_file)
              optimized_file = optimize(
                  original_file.file,
                  png_command="optipng -force -o7 '%(filename)s' "
              )
              self.assertTrue(original_file.size > optimized_file.size)
  