old_contents: from marvin import create_app
  
  import unittest
  
  class AppCreationTest(unittest.TestCase):
  
      def test_create_app(self):
          app = create_app(MY_CONFIG_VALUE='foo')
          self.assertEqual(app.config['MY_CONFIG_VALUE'], 'foo')
  
new_contents: from marvin import create_app
  
  import os
  import tempfile
  import unittest
  
  class AppCreationTest(unittest.TestCase):
  
      def setUp(self):
          self.config_file = tempfile.NamedTemporaryFile(delete=False)
          self.config_file.write('OTHER_CONFIG = "bar"'.encode('utf-8'))
          self.config_file.close()
  
  
      def tearDown(self):
          os.remove(self.config_file.name)
  
  
      def test_create_app(self):
          app = create_app(MY_CONFIG_VALUE='foo')
          self.assertEqual(app.config['MY_CONFIG_VALUE'], 'foo')
  
  
      def test_create_app_with_config_file(self):
          app = create_app(self.config_file.name)
          self.assertEqual(app.config['OTHER_CONFIG'], 'bar')
  
  
      def test_create_app_both(self):
          app = create_app(self.config_file.name, EXTRA_PARAM='baz')
          self.assertEqual(app.config['OTHER_CONFIG'], 'bar')
          self.assertEqual(app.config['EXTRA_PARAM'], 'baz')
  
subject: Add test for app creation with config file.