Engine: add stop loss integration (fixed & trailing) with tests

tests/risk/sizing/test_fixed.py

@@ -0,0 +1,39 @@
+import sys
+from pathlib import Path
+import pytest
+
+# Añadir raíz del proyecto al path
+sys.path.insert(0, str(Path(__file__).parent.parent.parent.parent))
+
+from src.risk.sizing.fixed import FixedPositionSizer
+
+
+def test_fixed_position_size_basic():
+    sizer = FixedPositionSizer(capital_fraction=0.5)
+
+    capital = 10_000
+    entry_price = 100
+
+    units = sizer.calculate_size(
+        capital=capital,
+        entry_price=entry_price
+    )
+
+    # 50% de 10k = 5k / 100 = 50 unidades
+    assert units == 50
+
+
+def test_fixed_position_size_full_capital():
+    sizer = FixedPositionSizer(capital_fraction=1.0)
+
+    units = sizer.calculate_size(
+        capital=10_000,
+        entry_price=200
+    )
+
+    assert units == 50
+
+
+def test_fixed_invalid_fraction():
+    with pytest.raises(ValueError):
+        FixedPositionSizer(capital_fraction=1.5)