Django test to detect uncreated/unmerged migration files

test_schema.py

from StringIO import StringIO

from django.core.management import call_command
from django.test import TestCase, override_settings


class TestMigrationDiscrepancies(TestCase):

    @override_settings(MIGRATION_MODULES={})
    def test_for_missing_migrations(self):
        output = StringIO()
        try:
            call_command('makemigrations', interactive=False, dry_run=True, exit_code=True, stdout=output)
        except SystemExit as e:
            # The exit code will be 1 when there are no missing migrations
            assert unicode(e) == '1'
        else:
            self.fail("There are missing migrations:\n %s" % output.getvalue())

For Django 2.0:

@override_settings(MIGRATION_MODULES={})
def test_for_missing_migrations(self):
    """ Test for missing migrations; the exit code will be non-zero.
    """
    output = StringIO()
    try:
        call_command('makemigrations', dry_run=True, check=True, stdout=output)
    except SystemExit:
        self.fail("There are missing migrations:\n %s" % output.getvalue())