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Sarj Sarj Sarj Standards

no-fixed-sleep-in-loop

Do not sleep for a fixed literal interval inside a production loop.

SARJ485 Rule source Tests Catalog JSON

Why

A polling or cleanup loop that sleeps for a literal interval gives tests no seam: every test that drives the loop pays the whole interval in real time, and replacing the module's sleep is a monkeypatch that SARJ445 forbids. Suites slow down one hardcoded interval at a time.

Fix

Route the interval through a constructor or configuration parameter, or call an injected sleeper or clock, so tests can pass a zero interval or a recording fake. Keep a literal only behind an exact SARJ485 suppression that names why the interval must never change under test.

Examples

Before — flagged A synchronous retry loop blocks for a hardcoded interval
app/health.py
import time




def wait_for_health(probe):
    for _ in range(30):
        if probe():
            return
        time.sleep(0.5)
After — preferred A synchronous retry loop calls an injected sleeper
app/health.py
from collections.abc import Callable




def wait_for_health(probe, sleep: Callable[[float], None]):
    for _ in range(30):
        if probe():
            return
        sleep(0.5)
Before — flagged A polling loop sleeps for a hardcoded interval
app/jobs.py
import asyncio




async def wait_until_done(job):
    while not await job.done():
        await asyncio.sleep(2)
After — preferred A polling loop sleeps for an injected interval
app/jobs.py
import asyncio




class JobWaiter:
    def __init__(self, poll_seconds: float) -> None:
        self._poll_seconds = poll_seconds


    async def wait_until_done(self, job):
        while not await job.done():
            await asyncio.sleep(self._poll_seconds)