# from __future__ import unicode_literals
# from django.test import TestCase
# from django.utils import six
# from rest_framework import serializers
# from rest_framework.compat import BytesIO
# import datetime


# class UploadedFile(object):
#     def __init__(self, file=None, created=None):
#         self.file = file
#         self.created = created or datetime.datetime.now()


# class UploadedFileSerializer(serializers.Serializer):
#     file = serializers.FileField(required=False)
#     created = serializers.DateTimeField()

#     def restore_object(self, attrs, instance=None):
#         if instance:
#             instance.file = attrs['file']
#             instance.created = attrs['created']
#             return instance
#         return UploadedFile(**attrs)


# class FileSerializerTests(TestCase):
#     def test_create(self):
#         now = datetime.datetime.now()
#         file = BytesIO(six.b('stuff'))
#         file.name = 'stuff.txt'
#         file.size = len(file.getvalue())
#         serializer = UploadedFileSerializer(data={'created': now}, files={'file': file})
#         uploaded_file = UploadedFile(file=file, created=now)
#         self.assertTrue(serializer.is_valid())
#         self.assertEqual(serializer.object.created, uploaded_file.created)
#         self.assertEqual(serializer.object.file, uploaded_file.file)
#         self.assertFalse(serializer.object is uploaded_file)

#     def test_creation_failure(self):
#         """
#         Passing files=None should result in an ValidationError

#         Regression test for:
#         https://github.com/tomchristie/django-rest-framework/issues/542
#         """
#         now = datetime.datetime.now()

#         serializer = UploadedFileSerializer(data={'created': now})
#         self.assertTrue(serializer.is_valid())
#         self.assertEqual(serializer.object.created, now)
#         self.assertIsNone(serializer.object.file)

#     def test_remove_with_empty_string(self):
#         """
#         Passing empty string as data should cause file to be removed

#         Test for:
#         https://github.com/tomchristie/django-rest-framework/issues/937
#         """
#         now = datetime.datetime.now()
#         file = BytesIO(six.b('stuff'))
#         file.name = 'stuff.txt'
#         file.size = len(file.getvalue())

#         uploaded_file = UploadedFile(file=file, created=now)

#         serializer = UploadedFileSerializer(instance=uploaded_file, data={'created': now, 'file': ''})
#         self.assertTrue(serializer.is_valid())
#         self.assertEqual(serializer.object.created, uploaded_file.created)
#         self.assertIsNone(serializer.object.file)

#     def test_validation_error_with_non_file(self):
#         """
#         Passing non-files should raise a validation error.
#         """
#         now = datetime.datetime.now()
#         errmsg = 'No file was submitted. Check the encoding type on the form.'

#         serializer = UploadedFileSerializer(data={'created': now, 'file': 'abc'})
#         self.assertFalse(serializer.is_valid())
#         self.assertEqual(serializer.errors, {'file': [errmsg]})

#     def test_validation_with_no_data(self):
#         """
#         Validation should still function when no data dictionary is provided.
#         """
#         uploaded_file = BytesIO(six.b('stuff'))
#         uploaded_file.name = 'stuff.txt'
#         uploaded_file.size = len(uploaded_file.getvalue())
#         serializer = UploadedFileSerializer(files={'file': uploaded_file})
#         self.assertFalse(serializer.is_valid())