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Make event triggering robust to (un)registration....
Make event triggering robust to (un)registration. Event callbacks can register or unregister new callbacks for the same event while executing, and the previous triggering implementation allowed for event callbacks to be inadvertently skipped. The fix is to make a copy of the list of callbacks before executing any of them. With this change, the resulting semantics are simple: any callbacks registered before triggering are executed, and any new callbacks registered are only visible at the next triggering of the event. Note that this could potentially break existing callers who expected newly-appended callbacks were immediately executed. Fixes #9447. Originally based on a patch by @marksandler2.

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test_hooks.py
81 lines | 2.4 KiB | text/x-python | PythonLexer
# -*- coding: utf-8 -*-
"""Tests for CommandChainDispatcher."""
from __future__ import absolute_import
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import nose.tools as nt
from IPython.core.error import TryNext
from IPython.core.hooks import CommandChainDispatcher
#-----------------------------------------------------------------------------
# Local utilities
#-----------------------------------------------------------------------------
# Define two classes, one which succeeds and one which raises TryNext. Each
# sets the attribute `called` to True when it is called.
class Okay(object):
def __init__(self, message):
self.message = message
self.called = False
def __call__(self):
self.called = True
return self.message
class Fail(object):
def __init__(self, message):
self.message = message
self.called = False
def __call__(self):
self.called = True
raise TryNext(self.message)
#-----------------------------------------------------------------------------
# Test functions
#-----------------------------------------------------------------------------
def test_command_chain_dispatcher_ff():
"""Test two failing hooks"""
fail1 = Fail(u'fail1')
fail2 = Fail(u'fail2')
dp = CommandChainDispatcher([(0, fail1),
(10, fail2)])
try:
dp()
except TryNext as e:
nt.assert_equal(str(e), u'fail2')
else:
assert False, "Expected exception was not raised."
nt.assert_true(fail1.called)
nt.assert_true(fail2.called)
def test_command_chain_dispatcher_fofo():
"""Test a mixture of failing and succeeding hooks."""
fail1 = Fail(u'fail1')
fail2 = Fail(u'fail2')
okay1 = Okay(u'okay1')
okay2 = Okay(u'okay2')
dp = CommandChainDispatcher([(0, fail1),
# (5, okay1), # add this later
(10, fail2),
(15, okay2)])
dp.add(okay1, 5)
nt.assert_equal(dp(), u'okay1')
nt.assert_true(fail1.called)
nt.assert_true(okay1.called)
nt.assert_false(fail2.called)
nt.assert_false(okay2.called)
def test_command_chain_dispatcher_eq_priority():
okay1 = Okay(u'okay1')
okay2 = Okay(u'okay2')
dp = CommandChainDispatcher([(1, okay1)])
dp.add(okay2, 1)