Add cx_Oracle 6 support

[Mariusz Felisiak]

cx_Oracle 6 causes a tests failures due to this change:

Prevent closing the connection when there are any open statements or LOBs and add new error “DPI-1054: connection cannot be closed when open statements or LOBs exist” when this situation is detected; this is needed to prevent crashes under certain conditions when statements or LOBs are being acted upon while at the same time (in another thread) a connection is being closed; it also prevents leaks of statements and LOBs when a connection is returned to a session pool. (see cx_Oracle ​release notes).

Sample exception:

Traceback (most recent call last):
  File "./runtests.py", line 478, in <module>
    options.exclude_tags,
  File "./runtests.py", line 286, in django_tests
    extra_tests=extra_tests,
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/test/runner.py", line 601, in run_tests
    old_config = self.setup_databases()
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/test/runner.py", line 548, in setup_databases
    self.parallel, **kwargs
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/test/utils.py", line 176, in setup_databases
    serialize=connection.settings_dict.get('TEST', {}).get('SERIALIZE', True),
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/backends/base/creation.py", line 54, in create_test_db
    self._create_test_db(verbosity, autoclobber, keepdb)
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/backends/oracle/creation.py", line 100, in _create_test_db
    self._maindb_connection.close()  # done with main user -- test user and tablespaces created
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/backends/base/base.py", line 281, in close
    self._close()
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/backends/base/base.py", line 243, in _close
    return self.connection.close()
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/jenkins/workspace/django-oracle-master/database/oracle12/label/trusty/python/python3.6/django/db/backends/base/base.py", line 243, in _close
    return self.connection.close()
django.db.utils.DatabaseError: DPI-1054: connection cannot be closed when open statements or LOBs exist}}}

[Mariusz Felisiak]

​PR

[GitHub <noreply@…>]

In 6784383:

Fixed #28498 -- Fixed test database creation with cx_Oracle 6.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 07e34f8b:

[1.11.x] Fixed #28498 -- Fixed test database creation with cx_Oracle 6.

Backport of 6784383e93d582f43f8cb5f7647a05645cbb339b from master

[Mariusz Felisiak]

Some tests are broken in stable/1.11.x branch on Python 2:

• backends.tests.BackendTestCase.test_unicode_password:

  Traceback (most recent call last):
    File "/home/jenkins/workspace/django-oracle-1.11/database/oracle12/label/trusty/python/python2.7/tests/backends/tests.py", line 736, in test_unicode_password
      self.fail("Unexpected error raised with unicode password: %s" % e)
  AssertionError: Unexpected error raised with unicode password: 'ascii' codec can't encode character u'\xe7' in position 4: ordinal not in range(128)
  

• db_functions.tests.FunctionTests.test_greatest_decimal_filter:

  Stacktrace
  
  Traceback (most recent call last):
    File "/home/jenkins/workspace/django-oracle-1.11/database/oracle12/label/trusty/python/python2.7/tests/expressions_case/tests.py", line 734, in test_update_decimal
      transform=attrgetter('integer', 'decimal')
    File "/home/jenkins/workspace/django-oracle-1.11/database/oracle12/label/trusty/python/python2.7/django/test/testcases.py", line 972, in assertQuerysetEqual
      return self.assertEqual(list(items), values, msg=msg)
  AssertionError: Lists differ: [(1, None), (2, Decimal('2.7')... != [(1, Decimal('1.1')), (2, Deci...
  
  First differing element 0:
  (1, None)
  (1, Decimal('1.1'))
  
  - [(1, None),
  + [(1, Decimal('1.1')),
  -  (2, Decimal('2.7')),
  ?                 ^
  
  +  (2, Decimal('2.2')),
  ?                 ^
  
     (3, None),
  -  (2, Decimal('2.7')),
  ?                 ^
  
  +  (2, Decimal('2.2')),
  ?                 ^
  
     (3, None),
     (3, None),
     (4, None)]
  

• db_functions.tests.FunctionTests.test_least_decimal_filter,
• db_functions.tests.FunctionTests.test_greatest_decimal_filter.

[Mariusz Felisiak]

​PR

[GitHub <noreply@…>]

In 0d21bdd3:

[1.11.x] Fixed #28498 -- Added support for cx_Oracle 6.

• Fixed implicit Decimal to float conversion when input_size is not

specified for Decimal parameters.

• Used encoding, nencoding parameters of cx_Oracle.connect() to support

unicode in DSN.

Thanks Tim Graham for the review.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 939d923e:

Refs #28498 -- Forwardported 1.11.5 release note.