Thanks to Adam Johnson, Carlton Gibson, Mariusz Felisiak, and Raphael
Michel for mentoring this Google Summer of Code 2019 project and
everyone else who helped with the patch.
Special thanks to Mads Jensen, Nick Pope, and Simon Charette for
extensive reviews.
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Using unittest.TestCase doesn't work properly when we perform db
queries. Moreover introspection is extremely slow on Oracle without
limiting models to a "backends" app.
Follow up to 8bcca47e83.
The sql_flush() positional argument sequences is replaced by the boolean
keyword-only argument reset_sequences. This ensures that the old
function signature can't be used by mistake when upgrading Django. When
the new argument is True, the sequences of the truncated tables will
reset. Using a single boolean value, rather than a list, allows making a
binary yes/no choice as to whether to reset all sequences rather than a
working on a completely different set.
Made deserialize_db_from_string() do not sort dependencies.
deserialize_db_from_string() doesn't use natural keys, so there is no
need to sort dependencies in serialize_db_to_string(). Moreover,
sorting models cause issues for circular dependencies.
Using Person in test_introspection caused removing constraints in
intermediate table for ManyToManyField in
VeryLongModelNameZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ that were
expected by other transaction tests. A model without any constraints
was used to prevent isolation issues.
deserialize_db_from_string() loads the full serialized database
contents, which might contain forward references and cycles. That
caused IntegrityError because constraints were checked immediately.
Now, it loads data in a transaction with constraint checks deferred
until the end of the transaction.
- Used selected "databases" instead of django.db.connections.
- Made routers in tests.migrations skip migrations on unexpected
databases.
- Added DiscoverRunnerGetDatabasesTests.assertSkippedDatabases() hook
which properly asserts messages about skipped databases.
Previously, this test could modify global state by changing
connection.settings_dict. This dict is a reference to the same dict as
django.db.connections.databases['default'], which is thus also changed.
The cleanup of this test would replace connection.settings_dic` with a
saved copy, which would leave the dict itself modified.
Additionally, create_test_db() would also modify these same dicts, as
well as settings.databases['default']['NAME'] by adding a "test_"
prefix, which is what can cause problems later.
This patch:
- makes a complete copy of the connection and work on that, to improve
isolation.
- calls destroy_test_db() to let that code clean up anything done by
create_test_db().
