new_contents: import os
  import unittest
  
  from node import data_uri
  
  TEST_TXT_FILE = "data_uri_test.txt"
  TEST_CONTENTS = "foo\n"
  
  class TestDataURI(unittest.TestCase):
  
      def setUp(self):
          with open(TEST_TXT_FILE, 'w') as f:
              f.write(TEST_CONTENTS)
  
      def tearDown(self):
          os.remove(TEST_TXT_FILE)
  
      def test_init_from_file(self):
          uri = data_uri.DataURI.from_file(TEST_TXT_FILE, base64=False)
          self.assertEqual(uri.data, TEST_CONTENTS)
          self.assertEqual(uri.mimetype, "text/plain")
          self.assertFalse(uri.is_base64)
  
      def test_init_from_args(self):
          data = "I like trains"
          charset = 'us-ascii'
          mime = 'text/plain'
          uri = data_uri.DataURI.make(
              mime,
              charset,
              base64=True,
              data=data)
  
          self.assertEqual(uri.data, data)
          self.assertEqual(uri.charset, charset)
          self.assertEqual(uri.mimetype, mime)
          self.assertTrue(uri.is_base64)
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Add tests for data_uri module