feat: realtime event-driven market data push framework

- Add EventBus for async publish/subscribe market events
- Add MarketEvent dataclass with tick/bar/signal/error types
- Add RealtimeStrategy base class with on_tick/on_bar callbacks
- Add emit_signal() for strategy-to-engine signal publishing
- Support per-symbol and global subscriptions
- API skeleton: transport-level subscription TBD
- Add 10 tests covering events, bus, and strategy

tests/unit/test_realtime.py

@@ -0,0 +1,164 @@
+"""单元测试：实时数据推送引擎."""
+
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+
+from easy_tdx.realtime.engine import (
+    EventBus,
+    EventType,
+    MarketEvent,
+    RealtimeStrategy,
+)
+
+
+class TestMarketEvent:
+    """测试行情事件."""
+
+    def test_event_creation(self) -> None:
+        """创建事件应正确设置字段."""
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+            price=10.5,
+            volume=1000,
+            timestamp=1700000000.0,
+        )
+
+        assert event.event_type == EventType.TICK
+        assert event.code == "000001"
+        assert event.market == "SZ"
+        assert event.price == 10.5
+
+    def test_event_default_values(self) -> None:
+        """默认值应为零和空字典."""
+        event = MarketEvent(
+            event_type=EventType.BAR,
+            code="600000",
+            market="SH",
+        )
+
+        assert event.price == 0.0
+        assert event.volume == 0.0
+        assert event.data == {}
+
+
+class TestEventBus:
+    """测试事件总线."""
+
+    def test_subscribe_and_count(self) -> None:
+        """订阅后计数应正确."""
+        bus = EventBus()
+        bus.subscribe("SZ000001", lambda e: None)
+        bus.subscribe("SZ000001", lambda e: None)
+        bus.subscribe("SH600000", lambda e: None)
+
+        assert bus.subscriber_count == 3
+
+    def test_subscribe_global(self) -> None:
+        """全局订阅应被计入."""
+        bus = EventBus()
+        bus.subscribe_all(lambda e: None)
+
+        assert bus.subscriber_count == 1
+
+    def test_unsubscribe(self) -> None:
+        """取消订阅后计数应减少."""
+        bus = EventBus()
+        handler = lambda e: None  # noqa: E731
+        bus.subscribe("SZ000001", handler)
+        bus.unsubscribe("SZ000001", handler)
+
+        assert bus.subscriber_count == 0
+
+    @pytest.mark.asyncio
+    async def test_publish_to_specific_subscriber(self) -> None:
+        """发布事件应通知特定订阅者."""
+        bus = EventBus()
+        received: list[MarketEvent] = []
+
+        async def handler(event: MarketEvent) -> None:
+            received.append(event)
+
+        bus.subscribe("SZ000001", handler)
+
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+            price=10.5,
+        )
+        await bus.publish(event)
+
+        assert len(received) == 1
+        assert received[0].price == 10.5
+
+    @pytest.mark.asyncio
+    async def test_publish_to_global_subscriber(self) -> None:
+        """全局订阅者应收到所有事件."""
+        bus = EventBus()
+        received: list[MarketEvent] = []
+
+        bus.subscribe_all(lambda e: received.append(e))
+
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+        )
+        await bus.publish(event)
+
+        assert len(received) == 1
+
+
+class TestRealtimeStrategy:
+    """测试实时策略基类."""
+
+    def test_on_tick_default_does_nothing(self) -> None:
+        """默认 on_tick 不应抛异常."""
+        strategy = RealtimeStrategy()
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+        )
+        strategy.on_tick(event)  # should not raise
+
+    @pytest.mark.asyncio
+    async def test_emit_signal_without_bus(self) -> None:
+        """无 event_bus 时 emit_signal 不应抛异常."""
+        strategy = RealtimeStrategy()
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+            price=10.0,
+        )
+        strategy.emit_signal("BUY", event)
+
+    @pytest.mark.asyncio
+    async def test_emit_signal_publishes_to_bus(self) -> None:
+        """emit_signal 应发布 SIGNAL 类型事件."""
+        bus = EventBus()
+        received: list[MarketEvent] = []
+        bus.subscribe("SZ000001", lambda e: received.append(e))
+
+        strategy = RealtimeStrategy(event_bus=bus)
+        event = MarketEvent(
+            event_type=EventType.TICK,
+            code="000001",
+            market="SZ",
+            price=10.0,
+            timestamp=1700000000.0,
+        )
+
+        strategy.emit_signal("BUY", event)
+        # Give the asyncio task time to run
+        await asyncio.sleep(0.1)
+
+        assert len(received) == 1
+        assert received[0].event_type == EventType.SIGNAL
+        assert received[0].data["direction"] == "BUY"