67 lines
3.1 KiB
Python
67 lines
3.1 KiB
Python
 
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"""R1 · R2 · R3 · R6: the engine with fake attempts and a fake clock (no waiting)."""
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from tretry.retry import Outcome, Policy, run_with_retry
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def failing(times, retryable=True):
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calls = []
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def attempt(timeout):
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calls.append(timeout)
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if len(calls) <= times:
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return Outcome(False, retryable, f"boom {len(calls)}")
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return Outcome(True, output="done")
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return attempt, calls
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def test_success_after_two_failures_waits_with_backoff(clock):
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attempt, calls = failing(2)
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result = run_with_retry(attempt, Policy(tries=4, backoff=0.5), sleep=clock.sleep, clock=clock)
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assert result.ok and result.output == "done" and len(calls) == 3
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assert clock.slept == [0.5, 1.0] # R1: 0.5 → 1.0 (doubles)
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def test_wait_has_a_cap_and_jitter_only_shortens():
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policy = Policy(tries=10, backoff=1, max_wait=4, jitter=0.5)
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assert [policy.wait(n, rand=lambda: 0.0) for n in range(1, 6)] == [1, 2, 4, 4, 4] # R1: cap
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assert policy.wait(3, rand=lambda: 1.0) == 2.0 # R2: up to 50% shorter
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def test_all_fail_then_fallback(clock):
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attempt, _ = failing(9)
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result = run_with_retry(attempt, Policy(tries=3), fallback=lambda t: Outcome(True, output="cached"),
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sleep=clock.sleep, clock=clock)
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assert result.ok and result.used_fallback and result.output == "cached" # R3
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assert [a.fallback for a in result.attempts] == [False, False, False, True]
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def test_not_retryable_stops_at_once_and_skips_fallback(clock):
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attempt, calls = failing(9, retryable=False)
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result = run_with_retry(attempt, Policy(tries=5), fallback=lambda t: Outcome(True, output="cached"),
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sleep=clock.sleep, clock=clock)
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assert not result.ok and len(calls) == 1 and result.stopped == "not-retryable" and not result.used_fallback
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def test_deadline_stops_before_a_wait_that_cannot_fit(clock):
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def slow(timeout):
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clock.now += 3 # every try takes 3 s
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return Outcome(False, True, "timeout")
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result = run_with_retry(slow, Policy(tries=5, backoff=1, deadline=7), sleep=clock.sleep, clock=clock)
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assert result.stopped == "deadline" and len(result.attempts) == 2 # R6: 3 + 1 + 3 = 7 → no third try
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assert result.seconds <= 7
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def test_deadline_shortens_the_last_timeout(clock):
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seen = []
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def attempt(timeout):
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seen.append(timeout)
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clock.now += timeout
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return Outcome(False, True, "timeout")
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run_with_retry(attempt, Policy(tries=3, backoff=0.5, deadline=5), per_try_timeout=3, sleep=clock.sleep, clock=clock)
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assert seen == [3, 1.5] # 3 + 0.5 wait → 1.5 s left for try 2
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def test_retry_after_is_respected_up_to_the_cap(clock):
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answers = [Outcome(False, True, "HTTP 429", status=429, retry_after=3), Outcome(True, output="ok")]
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result = run_with_retry(lambda t: answers.pop(0), Policy(tries=3, backoff=0.5, max_wait=8), sleep=clock.sleep, clock=clock)
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assert result.ok and clock.slept == [3] # R4: the server's 3 s, not our 0.5 s
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