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""" Test utilities
"""
# Authors: Deepak Surti, Ioannis Tziakos
# Copyright (c) 2015, Enthought, Inc.
# License: BSD Style.
import contextlib
import gc
import unittest
import weakref
@contextlib.contextmanager
def restore_gc_state():
"""Ensure that gc state is restored on exit of the with statement."""
originally_enabled = gc.isenabled()
try:
yield
finally:
if originally_enabled:
gc.enable()
else:
gc.disable()
class TestGarbageCollection(unittest.TestCase):
""" This is a base class to use when testing garbage collection.
See: tvtk.tests.test_garbage_collection
mayavi.tests.test_garbage_collection
"""
def check_object_garbage_collected(self, obj_create_fn, obj_close_fn=None):
""" Call this from a test function to test for garbage collection
passing the following parameters:
obj_create_fn: function
A function with no parameters that creates the object
obj_close_fn: function
A function of 1 parameter which is the object created by
obj_create_fn, to handling the object closing, if any.
"""
# given
object_collected = []
object_weakref = None
def object_collected_callback(weakref):
object_collected.append(True)
def do():
obj = obj_create_fn()
reference = weakref.ref(obj, object_collected_callback)
if obj_close_fn:
obj_close_fn(obj)
return reference
# when
with restore_gc_state():
gc.disable()
object_weakref = do()
# The object should have been collected.
self.assertTrue(object_collected[0])
self.assertIsNone(object_weakref())
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