class ContextTimeController(Thread):
"""
Executes a function in a new thread that uses a fake datetime.
This allows a test to manipulate time as perceived by the target function.
"""
"""Initializer
Behaves exactly like Thread.__init__ except that daemon defaults to
True.
target -- function to call in the thread
parent_context -- inherit dependencies injected into this context
"""
def __init__(self, target, *args, parent_context, **kwargs):
super().__init__(target=target, **kwargs)
self.exception_caught = None
self.value_returned = None
self.fake_datetime = FakeDatetime()
self._context = parent_context.spawn()
self._target = target
"""Advance the fake clock by the given interval
Raises a RuntimeError if the thread has not been started.
Keyword arguments can be anything accepted by datetime.timedelta.
"""
def advance(self, **kwargs):
if not self.ident:
raise RuntimeError(
"The thread must be started before advancing time")
self.fake_datetime.advance(**kwargs)
def run(self):
self._context.inject(datetime, self.fake_datetime)
self._context.attach_to_thread(self)
try:
self.value_returned = self._target()
except Exception as e:
self.exception_caught = e
def test_can_advance_by_arbitrary_days(self):
fake = FakeDatetime()
days = 8
start = fake.now()
fake.advance(days=days)
expect(fake.now()).to(equal(start + timedelta(days=days)))
def test_can_advance_by_arbitrary_hours(self):
fake = FakeDatetime()
hours = 23
start = fake.now()
fake.advance(hours=hours)
expect(fake.now()).to(equal(start + timedelta(hours=hours)))
def test_can_advance_by_arbitrary_minutes(self):
fake = FakeDatetime()
mins = 4
start = fake.now()
fake.advance(minutes=mins)
expect(fake.now()).to(equal(start + timedelta(minutes=mins)))
def test_can_advance_by_arbitrary_sec(self):
fake = FakeDatetime()
sec = 235
start = fake.now()
fake.advance(seconds=sec)
expect(fake.now()).to(equal(start + timedelta(seconds=sec)))
def test_can_advance_by_arbitrary_ms(self):
fake = FakeDatetime()
ms = 235
start = fake.now()
fake.advance(milliseconds=ms)
expect(fake.now()).to(equal(start + timedelta(milliseconds=ms)))
