  from django.db import connection, DatabaseError, IntegrityError
  from django.db.models.fields import IntegerField, TextField, CharField, SlugField
  from django.db.models.fields.related import ManyToManyField, ForeignKey
  from django.db.transaction import atomic
  from .models import Author, AuthorWithM2M, Book, BookWithSlug, BookWithM2M, Tag, TagIndexed, TagM2MTest, TagUniqueRename, UniqueTest
  
  
  class SchemaTests(TransactionTestCase):
      """
      Tests that the schema-alteration code works correctly.
 
</s> remove     models = [Author, AuthorWithM2M, Book, BookWithSlug, BookWithM2M, Tag, TagIndexed, TagM2MTest, TagUniqueRename, UniqueTest]
 </s> add     models = [
        Author, AuthorWithM2M, Book, BookWithLongName, BookWithSlug,
        BookWithM2M, Tag, TagIndexed, TagM2MTest, TagUniqueRename, UniqueTest,
    ] </s> remove             index_name = hashlib.md5(index_name).hexdigest()[:self.connection.features.max_index_name_length]
 </s> add             index_name = hashlib.md5(force_bytes(index_name)).hexdigest()[:self.connection.features.max_index_name_length]
from .models import (Author, AuthorWithM2M, Book, BookWithLongName,
    BookWithSlug, BookWithM2M, Tag, TagIndexed, TagM2MTest, TagUniqueRename,
    UniqueTest)
  from django.db import connection, DatabaseError, IntegrityError
  from django.db.models.fields import IntegerField, TextField, CharField, SlugField
  from django.db.models.fields.related import ManyToManyField, ForeignKey
  from django.db.transaction import atomic
from .models import (Author, AuthorWithM2M, Book, BookWithLongName,
    BookWithSlug, BookWithM2M, Tag, TagIndexed, TagM2MTest, TagUniqueRename,
    UniqueTest)
  
  
  class SchemaTests(TransactionTestCase):
      """
      Tests that the schema-alteration code works correctly.
keep keep keep keep replace keep keep keep keep keep
 Fixed #21497 -- Forced conversion to bytes for very long index names 
tests/schema/tests.py