Re: Flakey tests and django.db.utils.InterfaceError: connection already closed

A test project that reproduces the problem would be helpful.

On Tuesday, October 27, 2015 at 9:14:13 AM UTC-4, Christopher R. wrote:

Have you been able to fix the problem? I am encountering the same issue on both Django 1.8.4 and 1.8.5.

Any help would be appreciated.

On Thursday, October 8, 2015 at 3:38:16 PM UTC+1, thinkwell wrote:

I could use some assistance in troubleshooting a psycopg2.InterfaceError problem that has erratic behavior. Here is the test module suite that I'm running to test these models, and in this state all the tests in the module pass. However, it's extremely easy to trigger a psycopg2.InterfaceError, although not relating to the lines changed. For example, if I change:

class TestSilly(SimpleTestCase):
 
    def test_is_not_false(self):
        self.assertTrue(False is not True)

to

class TestSilly(TestCase):
 
    def test_is_not_false(self):
        self.assertTrue(False is not True)

 

Then this error is raised, but referencing TestPolicyModel instead of TestSilly!

======================================================================
ERROR: test_toggle_autofix (accounts.tests.test_models.TestPolicyModel)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/base.py", line 137, in _cursor
    return self.create_cursor()
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 212, in create_cursor
    cursor = self.connection.cursor()
psycopg2.InterfaceError: connection already closed

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "apps/accounts/tests/test_models.py", line 174, in test_toggle_autofix
    p = Policy.objects.first()
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 490, in first
    objects = list((self if self.ordered else self.order_by('pk'))[:1])
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 162, in __iter__
    self._fetch_all()
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 965, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 238, in iterator
    results = compiler.execute_sql()
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/sql/compiler.py", line 838, in execute_sql
    cursor = self.connection.cursor()
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/base.py", line 164, in cursor
    cursor = self.make_cursor(self._cursor())
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/base.py", line 137, in _cursor
    return self.create_cursor()
  File "/usr/local/lib/python3.4/dist-packages/django/db/utils.py", line 97, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/local/lib/python3.4/dist-packages/django/utils/six.py", line 658, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/base.py", line 137, in _cursor
    return self.create_cursor()
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 212, in create_cursor
    cursor = self.connection.cursor()
django.db.utils.InterfaceError: connection already closed

For another example, if I change

TestPolicyModel(TestCase)

to

TestPolicyModel(SimpleTestCase)

then, I get the following error regarding TestRedwoodModel

======================================================================
ERROR: setUpClass (accounts.tests.test_models.TestRedwoodModel)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/base.py", line 137, in _cursor
    return self.create_cursor()
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 212, in create_cursor
    cursor = self.connection.cursor()
psycopg2.InterfaceError: connection already closed

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "apps/accounts/tests/test_models.py", line 195, in setUpClass
    cls.ru = RedwoodUsers.objects.first()
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 490, in first
    objects = list((self if self.ordered else self.order_by(

...

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