Tyler
100 lines
2.7 KiB
Python
100 lines
2.7 KiB
Python
"""Tests for the in-process EventBus.
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These exercise the drop-oldest overflow strategy, per-kind fan-out, and
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the non-blocking publish contract. They are async because the bus
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exposes an async iterator for subscribers.
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"""
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from __future__ import annotations
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import asyncio
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import time
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import pytest
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from cyclone.pubsub import EventBus
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@pytest.mark.asyncio
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async def test_publish_no_subscribers_is_noop():
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bus = EventBus()
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# No subscribers at all — must not raise.
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await bus.publish("x", {"a": 1})
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@pytest.mark.asyncio
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async def test_publish_to_n_subscribers_delivers_to_all():
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bus = EventBus()
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queues = [bus.subscribe(["claim"]) for _ in range(3)]
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await bus.publish("claim", {"id": "C1"})
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received = [await asyncio.wait_for(q.__anext__(), timeout=0.5) for q in queues]
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for event in received:
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assert event == {"id": "C1", "_kind": "claim"}
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@pytest.mark.asyncio
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async def test_subscriber_only_receives_matching_kinds():
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bus = EventBus()
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queue = bus.subscribe(["a"])
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await bus.publish("b", {"n": 1})
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await bus.publish("a", {"n": 2})
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event = await asyncio.wait_for(queue.__anext__(), timeout=0.5)
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assert event == {"n": 2, "_kind": "a"}
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@pytest.mark.asyncio
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async def test_slow_subscriber_does_not_block_publish():
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bus = EventBus(max_queue_size=2)
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queue = bus.subscribe(["e"])
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async def emit():
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for i in range(3):
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await bus.publish("e", {"i": i})
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start = time.monotonic()
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await emit()
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elapsed = time.monotonic() - start
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# Publishing must not block even though the subscriber queue is full
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# after the second event; the drop-oldest policy keeps publishes non-blocking.
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assert elapsed < 0.05, f"publish blocked for {elapsed:.3f}s"
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# The slow subscriber retains only the last two events.
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seen = []
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for _ in range(2):
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seen.append(await asyncio.wait_for(queue.__anext__(), timeout=0.5))
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assert [e["i"] for e in seen] == [1, 2]
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@pytest.mark.asyncio
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async def test_queue_overflow_drops_oldest():
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bus = EventBus(max_queue_size=2)
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queue = bus.subscribe(["e"])
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for i in range(3):
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await bus.publish("e", {"i": i})
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seen = []
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for _ in range(2):
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seen.append(await asyncio.wait_for(queue.__anext__(), timeout=0.5))
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assert [e["i"] for e in seen] == [1, 2]
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@pytest.mark.asyncio
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async def test_multiple_concurrent_subscribers_each_get_all_events():
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bus = EventBus()
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queues = [bus.subscribe(["claim"]) for _ in range(2)]
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for i in range(5):
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await bus.publish("claim", {"i": i})
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for q in queues:
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seen = []
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for _ in range(5):
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seen.append(await asyncio.wait_for(q.__anext__(), timeout=0.5))
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assert [e["i"] for e in seen] == [0, 1, 2, 3, 4]
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