microdao-daarion/services/market-data-service/tests/test_bus_smoke.py

"""
Smoke test for the async event bus.
"""
import asyncio

import pytest

from app.core.bus import EventBus
from app.domain.events import TradeEvent, HeartbeatEvent, EventType


class MockConsumer:
    """Test consumer that collects events."""

    def __init__(self):
        self.events: list = []

    async def handle(self, event):
        self.events.append(event)


class FailingConsumer:
    """Consumer that always raises."""

    async def handle(self, event):
        raise ValueError("I always fail")


@pytest.mark.asyncio
async def test_bus_fanout():
    """Events are delivered to all consumers."""
    bus = EventBus()
    c1 = MockConsumer()
    c2 = MockConsumer()
    bus.add_consumer(c1)
    bus.add_consumer(c2)

    await bus.start()

    event = TradeEvent(
        provider="test",
        symbol="BTCUSDT",
        price=42000.0,
        size=1.5,
    )
    await bus.publish(event)

    # Give worker time to process
    await asyncio.sleep(0.1)
    await bus.stop()

    assert len(c1.events) == 1
    assert len(c2.events) == 1
    assert c1.events[0].symbol == "BTCUSDT"
    assert c2.events[0].price == 42000.0


@pytest.mark.asyncio
async def test_bus_failing_consumer_doesnt_block():
    """A failing consumer doesn't prevent others from receiving events."""
    bus = EventBus()
    good = MockConsumer()
    bad = FailingConsumer()
    bus.add_consumer(bad)
    bus.add_consumer(good)

    await bus.start()

    await bus.publish(HeartbeatEvent(provider="test"))
    await asyncio.sleep(0.1)
    await bus.stop()

    assert len(good.events) == 1
    assert good.events[0].event_type == EventType.HEARTBEAT


@pytest.mark.asyncio
async def test_bus_multiple_events():
    """Multiple events are delivered in order."""
    bus = EventBus()
    consumer = MockConsumer()
    bus.add_consumer(consumer)

    await bus.start()

    for i in range(10):
        await bus.publish(
            TradeEvent(
                provider="test",
                symbol=f"SYM{i}",
                price=float(i),
                size=1.0,
            )
        )

    await asyncio.sleep(0.2)
    await bus.stop()

    assert len(consumer.events) == 10
    symbols = [e.symbol for e in consumer.events]
    assert symbols == [f"SYM{i}" for i in range(10)]


@pytest.mark.asyncio
async def test_bus_queue_overflow():
    """Bus handles queue overflow without crashing."""
    bus = EventBus(queue_size=3)
    consumer = MockConsumer()
    bus.add_consumer(consumer)

    # Don't start worker — queue will fill up
    for i in range(10):
        await bus.publish(
            HeartbeatEvent(provider="test")
        )

    # Should not raise
    await bus.start()
    await asyncio.sleep(0.1)
    await bus.stop()

    # Some events were dropped, but consumer got the ones that fit
    assert len(consumer.events) >= 1


@pytest.mark.asyncio
async def test_bus_backpressure_drops_quotes_before_trades():
    """Under backpressure, quotes are dropped but trades survive."""
    from app.domain.events import QuoteEvent

    bus = EventBus(queue_size=10)
    consumer = MockConsumer()
    bus.add_consumer(consumer)

    # Fill queue to 100% with heartbeats (without starting worker)
    for _ in range(10):
        await bus.publish(HeartbeatEvent(provider="test"))

    # Now try to publish a quote — should be silently dropped (>90% fill)
    quote = QuoteEvent(
        provider="test", symbol="BTCUSDT",
        bid=70000.0, ask=70001.0, bid_size=1.0, ask_size=1.0,
    )
    await bus.publish(quote)

    # Start worker, drain existing events
    await bus.start()
    await asyncio.sleep(0.1)
    await bus.stop()

    # All received events should be heartbeats, quote was dropped
    types = [e.event_type for e in consumer.events]
    # The queue was full so older events get replaced; quote should NOT be there
    assert EventType.TRADE not in types  # no trades published
    # Verify no quotes survived (they are low-priority under pressure)
    # Note: with queue_size=10 and 10 heartbeats, queue was 100% full
    # Quote at fill=100% with priority=1 gets dropped


@pytest.mark.asyncio
async def test_bus_heartbeat_monitor_emits_on_silence():
    """Heartbeat monitor fires when a provider goes silent."""
    bus = EventBus(queue_size=100, heartbeat_interval=0.3)
    consumer = MockConsumer()
    bus.add_consumer(consumer)
    bus.register_provider("test_provider")

    await bus.start()

    # Don't send any events — just wait for heartbeat monitor
    await asyncio.sleep(0.8)
    await bus.stop()

    # Should have at least one synthetic heartbeat
    heartbeats = [e for e in consumer.events if e.event_type == EventType.HEARTBEAT]
    assert len(heartbeats) >= 1
    assert heartbeats[0].provider == "test_provider"


@pytest.mark.asyncio
async def test_bus_fill_percent():
    """fill_percent property works correctly."""
    bus = EventBus(queue_size=100)
    assert bus.fill_percent == 0.0

    for _ in range(50):
        await bus.publish(HeartbeatEvent(provider="test"))

    assert 0.49 <= bus.fill_percent <= 0.51