Avoid using code only for testing purposes

[fmigneault]

I believe that the following code should be simplified to only do what it is supposed to do.

twitcher/twitcher/models/__init__.py

Lines 53 to 82 in fe51e8f

	def add_tm_session(request):
	""" Request method that returns a SQLAlchemy session for a request.
	The SQLAlchemy session is managed by a Zope transaction, unless the request has been generated from a
	webtest.TestApp instance for functional testing. In this case:
	- Inspect request.environ dictionary for the SQLAlchemy session referenced by key db.session. Remove the
	session from the request's environment dictionary and return the session.
	- Use the session factory to generate and return a new SQLAlchemy session if there is no entry for db.session
	in the request environment dictionary.
	The webtest.TestApp instance should configure the environment dictionary as follows:
	`testapp = webtest.TestApp(app, extra_environ={'db.session': session, 'tm.active': True})`
	Setting tm.active to True causes the pyramid_tm tween to bypass generating a transaction for the SQLAlchemy
	session on the request.
	This code is taken from:
	https://groups.google.com/forum/#!topic/pylons-discuss/BZCeM_yejEE
	:param request: Pyramid Request instance
	:return: SQLAlchemy session.
	"""
	if 'paste.testing' in request.environ and request.environ['paste.testing'] is True:
	if 'db.session' in request.environ: # and 'db.tm' in request.environ:
	dbsession = request.environ['db.session']
	del request.environ['db.session']
	return dbsession
	session = get_tm_session(request.registry['dbsession_factory'], request.tm)
	return session

For testing, the mock module should be used to do exactly what the docstring says.
I think that creating a decorator function that does this mocking as required would be the best approach, as it would allow to do something like so:

@mock_db
def test_something():
 ...