celery/celery/tests/worker/test_request.py

# -*- coding: utf-8 -*-
from __future__ import absolute_import
from __future__ import with_statement

import anyjson
import os
import sys
import time

from datetime import datetime, timedelta

from kombu.transport.base import Message
from kombu.utils.encoding import from_utf8, default_encode
from mock import Mock, patch
from nose import SkipTest

from celery import current_app
from celery import states
from celery.app import app_or_default
from celery.concurrency.base import BasePool
from celery.datastructures import ExceptionInfo
from celery.exceptions import (RetryTaskError,
                               WorkerLostError, InvalidTaskError)
from celery.task.trace import eager_trace_task, TraceInfo, mro_lookup
from celery.result import AsyncResult
from celery.task import task as task_dec
from celery.task.base import Task
from celery.utils import uuid
from celery.worker import job as module
from celery.worker.job import Request, TaskRequest, execute_and_trace
from celery.worker.state import revoked

from celery.tests.utils import Case


scratch = {"ACK": False}
some_kwargs_scratchpad = {}


class test_mro_lookup(Case):

    def test_order(self):

        class A(object):
            pass

        class B(A):
            pass

        class C(B):
            pass

        class D(C):

            @classmethod
            def mro(cls):
                return ()

        A.x = 10
        self.assertEqual(mro_lookup(C, "x"), A)
        self.assertIsNone(mro_lookup(C, "x", stop=(A, )))
        B.x = 10
        self.assertEqual(mro_lookup(C, "x"), B)
        C.x = 10
        self.assertEqual(mro_lookup(C, "x"), C)
        self.assertIsNone(mro_lookup(D, "x"))


def jail(task_id, name, args, kwargs):
    return eager_trace_task(current_app.tasks[name],
                            task_id, args, kwargs, eager=False)[0]


def on_ack(*args, **kwargs):
    scratch["ACK"] = True


@task_dec(accept_magic_kwargs=False)
def mytask(i, **kwargs):
    return i ** i


@task_dec               # traverses coverage for decorator without parens
def mytask_no_kwargs(i):
    return i ** i


class MyTaskIgnoreResult(Task):
    ignore_result = True

    def run(self, i):
        return i ** i


@task_dec(accept_magic_kwargs=True)
def mytask_some_kwargs(i, logfile):
    some_kwargs_scratchpad["logfile"] = logfile
    return i ** i


@task_dec(accept_magic_kwargs=False)
def mytask_raising(i):
    raise KeyError(i)


class test_default_encode(Case):

    def setUp(self):
        if sys.version_info >= (3, 0):
            raise SkipTest("py3k: not relevant")

    def test_jython(self):
        prev, sys.platform = sys.platform, "java 1.6.1"
        try:
            self.assertEqual(default_encode("foo"), "foo")
        finally:
            sys.platform = prev

    def test_cython(self):
        prev, sys.platform = sys.platform, "darwin"
        gfe, sys.getfilesystemencoding = sys.getfilesystemencoding, \
                                         lambda: "utf-8"
        try:
            self.assertEqual(default_encode("foo"), "foo")
        finally:
            sys.platform = prev
            sys.getfilesystemencoding = gfe


class test_RetryTaskError(Case):

    def test_retry_task_error(self):
        try:
            raise Exception("foo")
        except Exception, exc:
            ret = RetryTaskError("Retrying task", exc)
            self.assertEqual(ret.exc, exc)


class test_trace_task(Case):

    @patch("celery.task.trace._logger")
    def test_process_cleanup_fails(self, _logger):
        backend = mytask.backend
        mytask.backend = Mock()
        mytask.backend.process_cleanup = Mock(side_effect=KeyError())
        try:
            tid = uuid()
            ret = jail(tid, mytask.name, [2], {})
            self.assertEqual(ret, 4)
            mytask.backend.store_result.assert_called_with(tid, 4,
                                                           states.SUCCESS)
            self.assertIn("Process cleanup failed",
                          _logger.error.call_args[0][0])
        finally:
            mytask.backend = backend

    def test_process_cleanup_BaseException(self):
        backend = mytask.backend
        mytask.backend = Mock()
        mytask.backend.process_cleanup = Mock(side_effect=SystemExit())
        try:
            with self.assertRaises(SystemExit):
                jail(uuid(), mytask.name, [2], {})
        finally:
            mytask.backend = backend

    def test_execute_jail_success(self):
        ret = jail(uuid(), mytask.name, [2], {})
        self.assertEqual(ret, 4)

    def test_marked_as_started(self):

        class Backend(mytask.backend.__class__):
            _started = []

            def store_result(self, tid, meta, state):
                if state == states.STARTED:
                    self._started.append(tid)

        prev, mytask.backend = mytask.backend, Backend()
        mytask.track_started = True

        try:
            tid = uuid()
            jail(tid, mytask.name, [2], {})
            self.assertIn(tid, Backend._started)

            mytask.ignore_result = True
            tid = uuid()
            jail(tid, mytask.name, [2], {})
            self.assertNotIn(tid, Backend._started)
        finally:
            mytask.backend = prev
            mytask.track_started = False
            mytask.ignore_result = False

    def test_execute_jail_failure(self):
        u = uuid()
        mytask_raising.request.update({"id": u})
        try:
            ret = jail(u, mytask_raising.name,
                    [4], {})
            self.assertIsInstance(ret, ExceptionInfo)
            self.assertTupleEqual(ret.exception.args, (4, ))
        finally:
            mytask_raising.request.clear()

    def test_execute_ignore_result(self):
        task_id = uuid()
        MyTaskIgnoreResult.request.update({"id": task_id})
        try:
            ret = jail(task_id, MyTaskIgnoreResult.name,
                       [4], {})
            self.assertEqual(ret, 256)
            self.assertFalse(AsyncResult(task_id).ready())
        finally:
            MyTaskIgnoreResult.request.clear()


class MockEventDispatcher(object):

    def __init__(self):
        self.sent = []
        self.enabled = True

    def send(self, event, **fields):
        self.sent.append(event)


class test_TaskRequest(Case):

    def test_task_wrapper_repr(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        self.assertTrue(repr(tw))

    @patch("celery.worker.job.kwdict")
    def test_kwdict(self, kwdict):

        prev, module.NEEDS_KWDICT = module.NEEDS_KWDICT, True
        try:
            TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
            self.assertTrue(kwdict.called)
        finally:
            module.NEEDS_KWDICT = prev

    def test_sets_store_errors(self):
        mytask.ignore_result = True
        try:
            tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
            self.assertFalse(tw.store_errors)
            mytask.store_errors_even_if_ignored = True
            tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
            self.assertTrue(tw.store_errors)
        finally:
            mytask.ignore_result = False
            mytask.store_errors_even_if_ignored = False

    def test_send_event(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.eventer = MockEventDispatcher()
        tw.send_event("task-frobulated")
        self.assertIn("task-frobulated", tw.eventer.sent)

    def test_on_retry(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.eventer = MockEventDispatcher()
        try:
            raise RetryTaskError("foo", KeyError("moofoobar"))
        except:
            einfo = ExceptionInfo(sys.exc_info())
            tw.on_failure(einfo)
            self.assertIn("task-retried", tw.eventer.sent)
            tw._does_info = False
            tw.on_failure(einfo)
            einfo.internal = True
            tw.on_failure(einfo)

    def test_compat_properties(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        self.assertEqual(tw.task_id, tw.id)
        self.assertEqual(tw.task_name, tw.name)
        tw.task_id = "ID"
        self.assertEqual(tw.id, "ID")
        tw.task_name = "NAME"
        self.assertEqual(tw.name, "NAME")

    def test_terminate__task_started(self):
        pool = Mock()
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = time.time()
        tw.worker_pid = 313
        tw.terminate(pool, signal="KILL")
        pool.terminate_job.assert_called_with(tw.worker_pid, "KILL")

    def test_terminate__task_reserved(self):
        pool = Mock()
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = None
        tw.terminate(pool, signal="KILL")
        self.assertFalse(pool.terminate_job.call_count)
        self.assertTupleEqual(tw._terminate_on_ack, (True, pool, "KILL"))
        tw.terminate(pool, signal="KILL")

    def test_revoked_expires_expired(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"},
                         expires=datetime.utcnow() - timedelta(days=1))
        tw.revoked()
        self.assertIn(tw.id, revoked)
        self.assertEqual(mytask.backend.get_status(tw.id),
                         states.REVOKED)

    def test_revoked_expires_not_expired(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"},
                         expires=datetime.utcnow() + timedelta(days=1))
        tw.revoked()
        self.assertNotIn(tw.id, revoked)
        self.assertNotEqual(mytask.backend.get_status(tw.id),
                         states.REVOKED)

    def test_revoked_expires_ignore_result(self):
        mytask.ignore_result = True
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"},
                         expires=datetime.utcnow() - timedelta(days=1))
        try:
            tw.revoked()
            self.assertIn(tw.id, revoked)
            self.assertNotEqual(mytask.backend.get_status(tw.id),
                                states.REVOKED)

        finally:
            mytask.ignore_result = False

    def test_send_email(self):
        app = app_or_default()
        old_mail_admins = app.mail_admins
        old_enable_mails = mytask.send_error_emails
        mail_sent = [False]

        def mock_mail_admins(*args, **kwargs):
            mail_sent[0] = True

        def get_ei():
            try:
                raise KeyError("moofoobar")
            except:
                return ExceptionInfo(sys.exc_info())

        app.mail_admins = mock_mail_admins
        mytask.send_error_emails = True
        try:
            tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})

            einfo = get_ei()
            tw.on_failure(einfo)
            self.assertTrue(mail_sent[0])

            einfo = get_ei()
            mail_sent[0] = False
            mytask.send_error_emails = False
            tw.on_failure(einfo)
            self.assertFalse(mail_sent[0])

            einfo = get_ei()
            mail_sent[0] = False
            mytask.send_error_emails = True
            mytask.error_whitelist = [KeyError]
            tw.on_failure(einfo)
            self.assertTrue(mail_sent[0])

            einfo = get_ei()
            mail_sent[0] = False
            mytask.send_error_emails = True
            mytask.error_whitelist = [SyntaxError]
            tw.on_failure(einfo)
            self.assertFalse(mail_sent[0])

        finally:
            app.mail_admins = old_mail_admins
            mytask.send_error_emails = old_enable_mails
            mytask.error_whitelist = ()

    def test_already_revoked(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw._already_revoked = True
        self.assertTrue(tw.revoked())

    def test_revoked(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        revoked.add(tw.id)
        self.assertTrue(tw.revoked())
        self.assertTrue(tw._already_revoked)
        self.assertTrue(tw.acknowledged)

    def test_execute_does_not_execute_revoked(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        revoked.add(tw.id)
        tw.execute()

    def test_execute_acks_late(self):
        mytask_raising.acks_late = True
        tw = TaskRequest(mytask_raising.name, uuid(), [1])
        try:
            tw.execute()
            self.assertTrue(tw.acknowledged)
            tw.task.accept_magic_kwargs = False
            tw.execute()
        finally:
            mytask_raising.acks_late = False

    def test_execute_using_pool_does_not_execute_revoked(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        revoked.add(tw.id)
        tw.execute_using_pool(None)

    def test_on_accepted_acks_early(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.on_accepted(pid=os.getpid(), time_accepted=time.time())
        self.assertTrue(tw.acknowledged)
        tw._does_debug = False
        tw.on_accepted(pid=os.getpid(), time_accepted=time.time())

    def test_on_accepted_acks_late(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        mytask.acks_late = True
        try:
            tw.on_accepted(pid=os.getpid(), time_accepted=time.time())
            self.assertFalse(tw.acknowledged)
        finally:
            mytask.acks_late = False

    def test_on_accepted_terminates(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        pool = Mock()
        tw.terminate(pool, signal="KILL")
        self.assertFalse(pool.terminate_job.call_count)
        tw.on_accepted(pid=314, time_accepted=time.time())
        pool.terminate_job.assert_called_with(314, "KILL")

    def test_on_success_acks_early(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        tw.on_success(42)
        tw._does_info = False
        tw.on_success(42)
        self.assertFalse(tw.acknowledged)

    def test_on_success_BaseException(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        with self.assertRaises(SystemExit):
            try:
                raise SystemExit()
            except SystemExit:
                tw.on_success(ExceptionInfo(sys.exc_info()))
            else:
                assert False

    def test_on_success_eventer(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        tw.eventer = Mock()
        tw.send_event = Mock()
        tw.on_success(42)
        self.assertTrue(tw.send_event.called)

    def test_on_success_when_failure(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        tw.on_failure = Mock()
        try:
            raise KeyError("foo")
        except Exception:
            tw.on_success(ExceptionInfo(sys.exc_info()))
            self.assertTrue(tw.on_failure.called)

    def test_on_success_acks_late(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        mytask.acks_late = True
        try:
            tw.on_success(42)
            self.assertTrue(tw.acknowledged)
        finally:
            mytask.acks_late = False

    def test_on_failure_WorkerLostError(self):

        def get_ei():
            try:
                raise WorkerLostError("do re mi")
            except WorkerLostError:
                return ExceptionInfo(sys.exc_info())

        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        exc_info = get_ei()
        tw.on_failure(exc_info)
        self.assertEqual(mytask.backend.get_status(tw.id),
                         states.FAILURE)

        mytask.ignore_result = True
        try:
            exc_info = get_ei()
            tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
            tw.on_failure(exc_info)
            self.assertEqual(mytask.backend.get_status(tw.id),
                             states.PENDING)
        finally:
            mytask.ignore_result = False

    def test_on_failure_acks_late(self):
        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.time_start = 1
        mytask.acks_late = True
        try:
            try:
                raise KeyError("foo")
            except KeyError:
                exc_info = ExceptionInfo(sys.exc_info())
                tw.on_failure(exc_info)
                self.assertTrue(tw.acknowledged)
        finally:
            mytask.acks_late = False

    def test_from_message_invalid_kwargs(self):
        body = dict(task=mytask.name, id=1, args=(), kwargs="foo")
        with self.assertRaises(InvalidTaskError):
            TaskRequest.from_message(None, body)

    @patch("celery.worker.job.error")
    @patch("celery.worker.job.warn")
    def test_on_timeout(self, warn, error):

        tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
        tw.on_timeout(soft=True, timeout=1337)
        self.assertIn("Soft time limit", warn.call_args[0][0])
        tw.on_timeout(soft=False, timeout=1337)
        self.assertIn("Hard time limit", error.call_args[0][0])
        self.assertEqual(mytask.backend.get_status(tw.id),
                         states.FAILURE)

        mytask.ignore_result = True
        try:
            tw = TaskRequest(mytask.name, uuid(), [1], {"f": "x"})
            tw.on_timeout(soft=True, timeout=1336)
            self.assertEqual(mytask.backend.get_status(tw.id),
                             states.PENDING)
        finally:
            mytask.ignore_result = False

    def test_execute_and_trace(self):
        res = execute_and_trace(mytask.name, uuid(), [4], {})
        self.assertEqual(res, 4 ** 4)

    def test_execute_safe_catches_exception(self):

        def _error_exec(self, *args, **kwargs):
            raise KeyError("baz")

        @task_dec
        def raising():
            raise KeyError("baz")
        raising.request = None

        with self.assertWarnsRegex(RuntimeWarning,
                r'Exception raised outside'):
            res = execute_and_trace(raising.name, uuid(),
                                    [], {})
            self.assertIsInstance(res, ExceptionInfo)

    def create_exception(self, exc):
        try:
            raise exc
        except exc.__class__:
            return sys.exc_info()

    def test_worker_task_trace_handle_retry(self):
        from celery.exceptions import RetryTaskError
        tid = uuid()
        mytask.request.update({"id": tid})
        try:
            _, value_, _ = self.create_exception(ValueError("foo"))
            einfo = self.create_exception(RetryTaskError(str(value_),
                                          exc=value_))
            w = TraceInfo(states.RETRY, einfo[1], einfo)
            w.handle_retry(mytask, store_errors=False)
            self.assertEqual(mytask.backend.get_status(tid), states.PENDING)
            w.handle_retry(mytask, store_errors=True)
            self.assertEqual(mytask.backend.get_status(tid), states.RETRY)
        finally:
            mytask.request.clear()

    def test_worker_task_trace_handle_failure(self):
        tid = uuid()
        mytask.request.update({"id": tid})
        try:
            einfo = self.create_exception(ValueError("foo"))
            w = TraceInfo(states.FAILURE, einfo[1], einfo)
            w.handle_failure(mytask, store_errors=False)
            self.assertEqual(mytask.backend.get_status(tid), states.PENDING)
            w.handle_failure(mytask, store_errors=True)
            self.assertEqual(mytask.backend.get_status(tid), states.FAILURE)
        finally:
            mytask.request.clear()

    def test_task_wrapper_mail_attrs(self):
        tw = TaskRequest(mytask.name, uuid(), [], {})
        x = tw.success_msg % {"name": tw.name,
                              "id": tw.id,
                              "return_value": 10,
                              "runtime": 0.3641}
        self.assertTrue(x)
        x = tw.error_msg % {"name": tw.name,
                           "id": tw.id,
                           "exc": "FOOBARBAZ",
                           "traceback": "foobarbaz"}
        self.assertTrue(x)

    def test_from_message(self):
        us = u"æØåveéðƒeæ"
        body = {"task": mytask.name, "id": uuid(),
                "args": [2], "kwargs": {us: "bar"}}
        m = Message(None, body=anyjson.dumps(body), backend="foo",
                          content_type="application/json",
                          content_encoding="utf-8")
        tw = TaskRequest.from_message(m, m.decode())
        self.assertIsInstance(tw, Request)
        self.assertEqual(tw.name, body["task"])
        self.assertEqual(tw.id, body["id"])
        self.assertEqual(tw.args, body["args"])
        us = from_utf8(us)
        if sys.version_info < (2, 6):
            self.assertEqual(tw.kwargs.keys()[0], us)
            self.assertIsInstance(tw.kwargs.keys()[0], str)

    def test_from_message_empty_args(self):
        body = {"task": mytask.name, "id": uuid()}
        m = Message(None, body=anyjson.dumps(body), backend="foo",
                          content_type="application/json",
                          content_encoding="utf-8")
        tw = TaskRequest.from_message(m, m.decode())
        self.assertIsInstance(tw, Request)
        self.assertEquals(tw.args, [])
        self.assertEquals(tw.kwargs, {})

    def test_from_message_missing_required_fields(self):
        body = {}
        m = Message(None, body=anyjson.dumps(body), backend="foo",
                          content_type="application/json",
                          content_encoding="utf-8")
        with self.assertRaises(KeyError):
            TaskRequest.from_message(m, m.decode())

    def test_from_message_nonexistant_task(self):
        body = {"task": "cu.mytask.doesnotexist", "id": uuid(),
                "args": [2], "kwargs": {u"æØåveéðƒeæ": "bar"}}
        m = Message(None, body=anyjson.dumps(body), backend="foo",
                          content_type="application/json",
                          content_encoding="utf-8")
        with self.assertRaises(KeyError):
            TaskRequest.from_message(m, m.decode())

    def test_execute(self):
        tid = uuid()
        tw = TaskRequest(mytask.name, tid, [4], {"f": "x"})
        self.assertEqual(tw.execute(), 256)
        meta = mytask.backend.get_task_meta(tid)
        self.assertEqual(meta["result"], 256)
        self.assertEqual(meta["status"], states.SUCCESS)

    def test_execute_success_no_kwargs(self):
        tid = uuid()
        tw = TaskRequest(mytask_no_kwargs.name, tid, [4], {})
        self.assertEqual(tw.execute(), 256)
        meta = mytask_no_kwargs.backend.get_task_meta(tid)
        self.assertEqual(meta["result"], 256)
        self.assertEqual(meta["status"], states.SUCCESS)

    def test_execute_success_some_kwargs(self):
        tid = uuid()
        tw = TaskRequest(mytask_some_kwargs.name, tid, [4], {})
        self.assertEqual(tw.execute(logfile="foobaz.log"), 256)
        meta = mytask_some_kwargs.backend.get_task_meta(tid)
        self.assertEqual(some_kwargs_scratchpad.get("logfile"), "foobaz.log")
        self.assertEqual(meta["result"], 256)
        self.assertEqual(meta["status"], states.SUCCESS)

    def test_execute_ack(self):
        tid = uuid()
        tw = TaskRequest(mytask.name, tid, [4], {"f": "x"},
                        on_ack=on_ack)
        self.assertEqual(tw.execute(), 256)
        meta = mytask.backend.get_task_meta(tid)
        self.assertTrue(scratch["ACK"])
        self.assertEqual(meta["result"], 256)
        self.assertEqual(meta["status"], states.SUCCESS)

    def test_execute_fail(self):
        tid = uuid()
        tw = TaskRequest(mytask_raising.name, tid, [4])
        self.assertIsInstance(tw.execute(), ExceptionInfo)
        meta = mytask_raising.backend.get_task_meta(tid)
        self.assertEqual(meta["status"], states.FAILURE)
        self.assertIsInstance(meta["result"], KeyError)

    def test_execute_using_pool(self):
        tid = uuid()
        tw = TaskRequest(mytask.name, tid, [4], {"f": "x"})

        class MockPool(BasePool):
            target = None
            args = None
            kwargs = None

            def __init__(self, *args, **kwargs):
                pass

            def apply_async(self, target, args=None, kwargs=None,
                    *margs, **mkwargs):
                self.target = target
                self.args = args
                self.kwargs = kwargs

        p = MockPool()
        tw.execute_using_pool(p)
        self.assertTrue(p.target)
        self.assertEqual(p.args[0], mytask.name)
        self.assertEqual(p.args[1], tid)
        self.assertEqual(p.args[2], [4])
        self.assertIn("f", p.args[3])
        self.assertIn([4], p.args)

        tw.task.accept_magic_kwargs = False
        tw.execute_using_pool(p)

    def test_default_kwargs(self):
        tid = uuid()
        tw = TaskRequest(mytask.name, tid, [4], {"f": "x"})
        self.assertDictEqual(
                tw.extend_with_default_kwargs(10, "some_logfile"), {
                    "f": "x",
                    "logfile": "some_logfile",
                    "loglevel": 10,
                    "task_id": tw.id,
                    "task_retries": 0,
                    "task_is_eager": False,
                    "delivery_info": {"exchange": None, "routing_key": None},
                    "task_name": tw.name})

    @patch("celery.worker.job.logger")
    def _test_on_failure(self, exception, logger):
        app = app_or_default()
        tid = uuid()
        tw = TaskRequest(mytask.name, tid, [4], {"f": "x"})
        try:
            raise exception
        except Exception:
            exc_info = ExceptionInfo(sys.exc_info())
            app.conf.CELERY_SEND_TASK_ERROR_EMAILS = True
            try:
                tw.on_failure(exc_info)
                self.assertTrue(logger.log.called)
                context = logger.log.call_args[0][2]
                self.assertEqual(mytask.name, context["name"])
                self.assertIn(tid, context["id"])
            finally:
                app.conf.CELERY_SEND_TASK_ERROR_EMAILS = False

    def test_on_failure(self):
        self._test_on_failure(Exception("Inside unit tests"))

    def test_on_failure_unicode_exception(self):
        self._test_on_failure(Exception(u"Бобры атакуют"))

    def test_on_failure_utf8_exception(self):
        self._test_on_failure(Exception(
            from_utf8(u"Бобры атакуют")))