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mads

py3: work around incompatibility between pytest, py3 inspect, and tg

Work around an issue that has been reported on
https://github.com/TurboGears/tg2/issues/118 :

.../site-packages/_pytest/doctest.py:381: in _mock_aware_unwrap
return real_unwrap(obj, stop=_is_mocked)
/usr/lib64/python3.7/inspect.py:511: in unwrap
while _is_wrapper(func):
/usr/lib64/python3.7/inspect.py:505: in _is_wrapper
return hasattr(f, '__wrapped__') and not stop(f)
.../site-packages/tg/support/objectproxy.py:19: in __getattr__
return getattr(self._current_obj(), attr)
.../site-packages/tg/request_local.py:240: in _current_obj
return getattr(context, self.name)
.../site-packages/tg/support/objectproxy.py:19: in __getattr__
return getattr(self._current_obj(), attr)
.../site-packages/tg/support/registry.py:72: in _current_obj
'thread' % self.____name__)
E TypeError: No object (name: context) has been registered for this thread

pytest's doctest support is (in _mock_aware_unwrap) using py3 inspect.

Inside inspect, _is_wrapper will do an innocent looking:
hasattr(f, '__wrapped__')

But if the code under test has un (unused) import of a tg context (such as
tg.request), it is no longer so innocent. tg will throw:
TypeError: No object (name: context) has been registered for this thread
(which in py2 would have caught by hasattr, but not in py3.)

pytest will thus fail already in the "collecting ..." phase.

To work around that, use the hack of pushing a tg context in the top level
pytest_configure.

=======================
Database schema changes
=======================

Kallithea uses Alembic for :ref:`database migrations <upgrade_db>`
(upgrades and downgrades).

If you are developing a Kallithea feature that requires database schema
changes, you should make a matching Alembic database migration script:

1. :ref:`Create a Kallithea configuration and database <setup>` for testing
   the migration script, or use existing ``development.ini`` setup.

   Ensure that this database is up to date with the latest database
   schema *before* the changes you're currently developing. (Do not
   create the database while your new schema changes are applied.)

2. Create a separate throwaway configuration for iterating on the actual
   database changes::

    kallithea-cli config-create temp.ini

   Edit the file to change database settings. SQLite is typically fine,
   but make sure to change the path to e.g. ``temp.db``, to avoid
   clobbering any existing database file.

3. Make your code changes (including database schema changes in ``db.py``).

4. After every database schema change, recreate the throwaway database
   to test the changes::

    rm temp.db
    kallithea-cli db-create -c temp.ini --repos=/var/repos --user=doe --email doe@example.com --password=123456 --no-public-access --force-yes
    kallithea-cli repo-scan -c temp.ini

5. Once satisfied with the schema changes, auto-generate a draft Alembic
   script using the development database that has *not* been upgraded.
   (The generated script will upgrade the database to match the code.)

   ::

    alembic -c development.ini revision -m "area: add cool feature" --autogenerate

6. Edit the script to clean it up and fix any problems.

   Note that for changes that simply add columns, it may be appropriate
   to not remove them in the downgrade script (and instead do nothing),
   to avoid the loss of data. Unknown columns will simply be ignored by
   Kallithea versions predating your changes.

7. Run ``alembic -c development.ini upgrade head`` to apply changes to
   the (non-throwaway) database, and test the upgrade script. Also test
   downgrades.

   The included ``development.ini`` has full SQL logging enabled. If
   you're using another configuration file, you may want to enable it
   by setting ``level = DEBUG`` in section ``[handler_console_sql]``.

The Alembic migration script should be committed in the same revision as
the database schema (``db.py``) changes.

See the `Alembic documentation`__ for more information, in particular
the tutorial and the section about auto-generating migration scripts.

.. __: http://alembic.zzzcomputing.com/en/latest/


Troubleshooting
---------------

* If ``alembic --autogenerate`` responds "Target database is not up to
  date", you need to either first use Alembic to upgrade the database
  to the most recent version (before your changes), or recreate the
  database from scratch (without your schema changes applied).