feat(trader): PositionLedger 单标的持仓(T+1冻结/均价)

tests/trader/test_position_ledger.py

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+"""PositionLedger 单标的持仓对象测试（raw 计均价、T+1 冻结）。"""
+import pytest
+
+from sanguo_trader.position_ledger import PositionLedger
+
+
+def test_new_position_empty():
+    p = PositionLedger(symbol="600000")
+    assert p.volume == 0
+    assert p.frozen == 0
+    assert p.avg_price == 0.0
+    assert p.available == 0
+
+
+def test_buy_sets_avg_price_and_freezes():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(price=10.0, volume=100)
+    assert p.volume == 100
+    assert p.frozen == 100          # T+1：买入当日冻结
+    assert p.available == 0         # 当日不可卖
+    assert p.avg_price == 10.0
+
+
+def test_avg_price_weighted_on_add():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    p.unfreeze()                    # 次日解冻
+    p.apply_buy(12.0, 100)
+    assert p.avg_price == 11.0      # (10*100 + 12*100)/200
+    assert p.volume == 200
+    # 新买的 100 又被冻结（T+1）
+    assert p.frozen == 100
+    assert p.available == 100
+
+
+def test_cannot_sell_frozen():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    assert p.frozen == 100
+    assert p.available == 0         # 当日不可卖
+
+
+def test_unfreeze_makes_available():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    p.unfreeze()
+    assert p.frozen == 0
+    assert p.available == 100
+
+
+def test_sell_reduces_volume():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 200)
+    p.unfreeze()
+    p.apply_sell(11.0, 100)
+    assert p.volume == 100
+    assert p.available == 100
+
+
+def test_sell_odd_lot_allowed():
+    """A 股卖出允许零股（退出持仓的基本操作）。"""
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 200)
+    p.unfreeze()
+    p.apply_sell(11.0, 50)          # 50 股零股
+    assert p.volume == 150
+
+
+def test_sell_over_available_raises():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    p.unfreeze()
+    with pytest.raises(ValueError, match="available"):
+        p.apply_sell(11.0, 200)
+
+
+def test_sell_frozen_raises():
+    """T+1：当日买入冻结，卖出冻结量必报错。"""
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    with pytest.raises(ValueError):
+        p.apply_sell(11.0, 50)
+
+
+def test_clear_position_avg_price_resets():
+    p = PositionLedger(symbol="600000")
+    p.apply_buy(10.0, 100)
+    p.unfreeze()
+    p.apply_sell(11.0, 100)
+    assert p.volume == 0
+    assert p.avg_price == 0.0