id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
33153	"""database table is locked"" error on SQLite when testing with mirror database"	Adam Johnson	nobody	"Requirements:
* project uses SQLite for database
* has a ""replica"" db alias set up as test mirror of default
* `TestCase` has `databases = [""default"", ""replica""]`
* Model is either from or two in a FK relationship
* `TestCase` tries to create an instance of that model

Result: The SQLite foreign key check, `PRAGMA foreign_key_check`, fails with an `OperationalError` like:

{{{
Traceback (most recent call last):
  File ""/.../site-packages/django/test/testcases.py"", line 278, in _setup_and_call
    self._post_teardown()
  File ""/.../site-packages/django/test/testcases.py"", line 1023, in _post_teardown
    self._fixture_teardown()
  File ""/.../site-packages/django/test/testcases.py"", line 1266, in _fixture_teardown
    connections[db_name].check_constraints()
  File ""/.../site-packages/django/db/backends/sqlite3/base.py"", line 322, in check_constraints
    violations = cursor.execute('PRAGMA foreign_key_check').fetchall()
  File ""/.../site-packages/django/db/backends/utils.py"", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File ""/.../site-packages/django/db/backends/utils.py"", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File ""/.../site-packages/django/db/backends/utils.py"", line 84, in _execute
    return self.cursor.execute(sql, params)
  File ""/.../site-packages/django/db/utils.py"", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File ""/.../site-packages/django/db/backends/utils.py"", line 82, in _execute
    return self.cursor.execute(sql)
  File ""/.../site-packages/django/db/backends/sqlite3/base.py"", line 414, in execute
    return Database.Cursor.execute(self, query)
django.db.utils.OperationalError: database table is locked: core_author
}}}

Reproduction project: https://github.com/adamchainz/django-ticket-33153 . Simply run `./manage.py test` to see the above exception.

Removing the FK from the model, the `""replica""` entry in `AuthorTests.databases`, or the mirror declaration in `settings.py:DATABASES` causes the test to pass."	Bug	closed	Testing framework	dev	Normal	duplicate			Unreviewed	0	0	0	0	0	0