def test__cannot_add_task_when_queue_is_full(self):
service = DatabaseTasksService(0)
service.startService()
try:
event = threading.Event()
service.addTask(event.wait)
try:
self.assertRaises(QueueOverflow, service.addTask, noop)
finally:
event.set()
finally:
service.stopService()
def test__failure_in_task_is_logged(self):
logger = self.useFixture(TwistedLoggerFixture())
service = DatabaseTasksService()
service.startService()
try:
service.addTask(lambda: 0 / 0)
finally:
service.stopService()
self.assertDocTestMatches(
"""\
...Unhandled failure in database task.
Traceback (most recent call last):
...
builtins.ZeroDivisionError: ...
""", logger.output)
def test__tasks_are_all_run_before_shutdown_completes(self):
service = DatabaseTasksService()
service.startService()
try:
queue = service.queue
event = threading.Event()
count = random.randint(20, 40)
for _ in range(count):
service.addTask(event.wait)
# The queue has `count` tasks (or `count - 1` tasks; the first may
# have already been pulled off the queue) still pending.
self.assertThat(queue.pending,
MatchesAny(HasLength(count), HasLength(count - 1)))
finally:
event.set()
service.stopService()
# The queue is empty and nothing is waiting.
self.assertThat(queue,
MatchesStructure.byEquality(waiting=[], pending=[]))
def test_failure_in_added_task_does_not_crash_service(self):
things = [] # This will be populated by tasks.
exception_type = factory.make_exception_type()
def be_bad():
raise exception_type("I'm bad, so bad.")
service = DatabaseTasksService()
service.startService()
try:
service.addTask(things.append, 1)
service.addTask(be_bad)
service.addTask(things.append, 2)
finally:
service.stopService()
self.assertThat(things, Equals([1, 2]))