- 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.
This reverts commits b3b1d3d45fc066367f4fcacf0b06f72fcd00a9c6 and
9fa0d3786febf36c87ef059a39115aa1ce3326e8 due to reverse build failures
for which a solution isn't forthcoming.
Data loaded in migrations were restored at the beginning of each
TransactionTestCase and all the tables are truncated at the end of
these test cases. If there was a TransactionTestCase at the end of
the test suite, the migrated data weren't restored in the database
(especially unexpected when using --keepdb). Now data is restored
at the end of each TransactionTestCase.
When using a TransactionTestCase with serialized_rollback=True,
after creating the database and running its migrations (along with
emitting the post_migrate signal), the contents of the database
are serialized to _test_serialized_contents.
After the first test case, _fixture_teardown() would flush the
tables but then the post_migrate signal would be emitted and new
rows (with new PKs) would be created in the django_content_type
table. Then in any subsequent test cases in a suite,
_fixture_setup() attempts to deserialize the content of
_test_serialized_contents, but these rows are identical to the
rows already in the database except for their PKs. This causes an
IntegrityError due to the unique constraint in the
django_content_type table.
This change made it so that in the above scenario the post_migrate
signal is not emitted after flushing the tables, since it will be
repopulated during fixture_setup().
