Fixed two test failures under Oracle

# -*- encoding: utf-8 -*-

from __future__ import unicode_literals

import unittest

from django.core.checks import Error

from django.core.exceptions import ImproperlyConfigured

from django.db import models

from django.db import connection, models

from .base import IsolatedModelsTestCase

class AutoFieldTests(IsolatedModelsTestCase):

    def test_valid_case(self):

        ]

        self.assertEqual(errors, expected)

    @unittest.skipUnless(connection.vendor == 'mysql',

                         "Test valid only for MySQL")

    def test_too_long_char_field_under_mysql(self):

        from django.db.backends.mysql.validation import DatabaseValidation

        # Ensure the field is right afterwards

        columns = self.column_classes(Author)

        self.assertEqual(columns['surname'][0], "CharField")

        self.assertEqual(columns['surname'][1][6], False)

        self.assertEqual(columns['surname'][1][6],

                         connection.features.interprets_empty_strings_as_nulls)

    def test_alter(self):

        """