cleveragents-core/tests/events/test_event_bus_semantics.py

from __future__ import annotations

from collections.abc import Callable

from cleveragents.a2a.events import A2aEventQueue, EventBusBridge
from cleveragents.application.services.fix_then_revalidate import (
    FixThenRevalidateOrchestrator,
)
from cleveragents.application.services.validation_pipeline import ValidationPipeline
from cleveragents.infrastructure.events.models import DomainEvent
from cleveragents.infrastructure.events.reactive import ReactiveEventBus
from cleveragents.infrastructure.events.types import EventType


def _event(event_type: EventType = EventType.PLAN_CREATED) -> DomainEvent:
    return DomainEvent(event_type=event_type)


def _pipeline() -> ValidationPipeline:
    return ValidationPipeline(commands=[], executor=lambda _name, _args: {})


def test_reactive_event_bus_close_completes_and_rejects_later_emit() -> None:
    bus = ReactiveEventBus()
    completed: list[bool] = []
    bus.stream.subscribe(on_completed=lambda: completed.append(True))

    bus.close()

    assert completed == [True]
    try:
        bus.emit(_event())
    except RuntimeError:
        pass
    else:
        raise AssertionError("emit after close should raise RuntimeError")


def test_reactive_event_bus_context_manager_closes_bus() -> None:
    bus = ReactiveEventBus()
    completed: list[bool] = []
    bus.stream.subscribe(on_completed=lambda: completed.append(True))

    with bus as entered:
        assert entered is bus

    assert bus._closed is True
    assert completed == [True]


class _TypedEventBus:
    def __init__(self) -> None:
        self.handlers: dict[EventType, list[Callable[[DomainEvent], None]]] = {}

    def emit(self, event: DomainEvent) -> None:
        for handler in self.handlers.get(event.event_type, []):
            handler(event)

    def subscribe(
        self, event_type: EventType, handler: Callable[[DomainEvent], None]
    ) -> None:
        self.handlers.setdefault(event_type, []).append(handler)

    def unsubscribe(
        self, event_type: EventType, handler: Callable[[DomainEvent], None]
    ) -> bool:
        handlers = self.handlers.get(event_type, [])
        try:
            handlers.remove(handler)
        except ValueError:
            return False
        return True


def test_event_bus_bridge_unsubscribes_from_typed_event_bus() -> None:
    bus = _TypedEventBus()
    queue = A2aEventQueue()
    bridge = EventBusBridge(bus, queue)

    bridge.start()
    bus.emit(_event())
    bridge.stop()
    bus.emit(_event())

    assert len(queue.get_events()) == 1
    assert all(not handlers for handlers in bus.handlers.values())


class _DisposableSubscription:
    def __init__(self) -> None:
        self.disposed = False

    def dispose(self) -> None:
        self.disposed = True


class _LegacyEventBus:
    def __init__(self) -> None:
        self.callback: Callable[[DomainEvent], None] | None = None
        self.subscription = _DisposableSubscription()

    def subscribe(self, callback: Callable[[DomainEvent], None]) -> object:
        self.callback = callback
        return self.subscription


def test_event_bus_bridge_still_supports_disposable_subscription_bus() -> None:
    bus = _LegacyEventBus()
    queue = A2aEventQueue()
    bridge = EventBusBridge(bus, queue)

    bridge.start()
    assert bus.callback is not None
    bus.callback(_event())
    bridge.stop()

    assert len(queue.get_events()) == 1
    assert bus.subscription.disposed is True
    assert bridge._subscription is None


class _EmitOnlyBus:
    def emit(self, event: DomainEvent) -> None:
        pass


def test_fix_then_revalidate_accepts_emit_only_event_sink() -> None:
    orchestrator = FixThenRevalidateOrchestrator(
        validation_pipeline=_pipeline(),
        event_bus=_EmitOnlyBus(),  # type: ignore[arg-type]
    )

    assert orchestrator.event_bus is not None