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Refactor time-based tests to use fake and sharp loop time #881

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@nolar nolar commented Dec 26, 2021

Utilise a new library — https://github.com/nolar/looptime — to have a fake time in event loops. The library does a lot of things, but the most important one is the sharp time with predictable steps with no code overhead included, which is typically random.

Everything else goes as a side-effect: e.g. the fast execution of such tests with zero real-time for any fake duration of loop time, convenient looptime fixture for assertions, etc.

This PR also demonstrates how the tests can be rewritten to use the provided looptime's features (and is mentioned in its README).

Fixes #212; related: #338

@nolar nolar added the automation CI/CD: testing, linting, releasing automatically label Dec 26, 2021
@nolar nolar force-pushed the faketime branch 3 times, most recently from e0f78f3 to 9c8ab16 Compare December 31, 2021 21:01
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lgtm-com bot commented Jul 24, 2022

This pull request introduces 1 alert when merging 420fa17 into 7b45690 - view on LGTM.com

new alerts:

  • 1 for Unused import

Otherwise, some tests may populate the cluster-scoped URLs while consuming the namespace-scoped URLs and thus catching errors, which are cryptic and hard to debug.

Signed-off-by: Sergey Vasilyev <[email protected]>
nolar added 10 commits July 30, 2023 21:06
…lds to the implementation

Signed-off-by: Sergey Vasilyev <[email protected]>
…tervals

The routines that depend only on the internal intervals and durations should use the internal loop time only — which can be later faked by e.g. `looptime`.

If the system or process time is used, these routines fall out of time-faking and might take many more cycles to reach the desired real-world timestamp (just by letting the real time flow naturally).

This does NOT cover the cases with intervals and durations based on the global time (i.e. UTC clock) — e.g. handlers' timeouts, retries, etc.

Signed-off-by: Sergey Vasilyev <[email protected]>
Utilise a new library — https://github.com/nolar/looptime — to have a fake time in event loops. The library does a lot of things, but the most important one is the sharp time with predictable steps with **no code overhead included**, which is typically random.

Everything else goes as a side-effect: e.g. the fast execution of such tests with zero real-time for any fake duration of loop time, convenient `looptime` fixture for assertions, etc.

Signed-off-by: Sergey Vasilyev <[email protected]>
await simulate_cycle(event_object)

assert k8s_mocked.sleep.call_count == 0
assert looptime == 1.23 # i.e. no additional sleeps happened

Check warning

Code scanning / CodeQL

Redundant comparison

Test is always true, because of [this condition](1).
await simulate_cycle(event_object)
await dummy.wait_for_daemon_done()

assert k8s_mocked.sleep.call_count == 0
assert looptime == 1.23 + 4.56 # i.e. not additional sleeps happened

Check warning

Code scanning / CodeQL

Redundant comparison

Test is always true, because of [this condition](1).
assert timer.seconds < CODE_OVERHEAD # near-instant
assert mock.call_args[0][0] == 'cancelled'
await scheduler.close()
assert looptime == 0

Check warning

Code scanning / CodeQL

Redundant comparison

Test is always true, because of [this condition](1).
assert mock.call_args[0][0] == 'finished'
await flag2.wait()
assert looptime == 123
assert mock.call_args_list[1][0][0] == 'finished'

Check warning

Code scanning / CodeQL

Unreachable code

This statement is unreachable.
sleep.return_value = 55 # simulated sleep time left
async with throttled(throttler=throttler, logger=logger, delays=[123, 234], wakeup=wakeup):
raise Exception()

await asyncio.sleep(77)

Check warning

Code scanning / CodeQL

Unreachable code

This statement is unreachable.
sleep.return_value = 55 # simulated sleep time left
async with throttled(throttler=throttler, logger=logger, delays=[123, 234], wakeup=wakeup):
raise Exception()

await asyncio.sleep(77)

Check warning

Code scanning / CodeQL

Unreachable code

This statement is unreachable.
sleep.return_value = 55 # simulated sleep time left
async with throttled(throttler=throttler, logger=logger, delays=[123, 234], wakeup=wakeup):
raise Exception()

await asyncio.sleep(1000)

Check warning

Code scanning / CodeQL

Unreachable code

This statement is unreachable.
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Stabilise the time-based tests with asyncio sleeps/timeouts
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