feat: planner cost+savings estimator against ingredient_grocery_match

backend/tests/test_planner_cost.py

@@ -0,0 +1,80 @@
+from decimal import Decimal
+from uuid import uuid4
+
+import pytest
+
+from app.services.planner.cost import compute_recipe_cost
+from app.services.planner.types import RecipeCost
+
+
+def _ingredient(ing_id, qty=1.0, unit=None):
+    return {"ingredient_id": ing_id, "qty": qty, "unit": unit}
+
+
+def _match(grocery_id, name, current, regular, is_on_sale, confidence=0.9):
+    return {
+        "grocery_item_id": grocery_id,
+        "grocery_item_name": name,
+        "current_price": Decimal(str(current)),
+        "regular_price": Decimal(str(regular)),
+        "is_on_sale": is_on_sale,
+        "confidence": Decimal(str(confidence)),
+    }
+
+
+def test_compute_recipe_cost_sums_ingredient_costs():
+    recipe_id = uuid4()
+    i1, i2 = uuid4(), uuid4()
+    g1, g2 = uuid4(), uuid4()
+    matches = {
+        i1: [_match(g1, "Chicken", current=4.00, regular=5.00, is_on_sale=True)],
+        i2: [_match(g2, "Olive Oil", current=8.00, regular=8.00, is_on_sale=False)],
+    }
+    pantry_ingredient_ids = set()
+
+    result = compute_recipe_cost(
+        recipe_id=recipe_id,
+        ingredients=[_ingredient(i1, qty=2.0), _ingredient(i2, qty=1.0)],
+        match_index=matches,
+        pantry_ingredient_ids=pantry_ingredient_ids,
+    )
+
+    assert isinstance(result, RecipeCost)
+    assert result.recipe_id == recipe_id
+    assert result.total_ingredient_count == 2
+    assert result.matched_ingredient_count == 2
+    assert result.sale_ingredient_count == 1
+    assert result.total_cost == Decimal("16.00")  # 2*4 + 1*8
+    assert result.total_savings == Decimal("2.00")  # 2*(5-4)
+
+
+def test_unmatched_ingredient_zero_cost_and_savings():
+    recipe_id = uuid4()
+    i1 = uuid4()
+    result = compute_recipe_cost(
+        recipe_id=recipe_id,
+        ingredients=[_ingredient(i1, qty=1.0)],
+        match_index={},
+        pantry_ingredient_ids=set(),
+    )
+    assert result.matched_ingredient_count == 0
+    assert result.total_cost == Decimal("0.00")
+    assert result.total_savings == Decimal("0.00")
+
+
+def test_pantry_hits_counted():
+    recipe_id = uuid4()
+    i1, i2 = uuid4(), uuid4()
+    g1, g2 = uuid4(), uuid4()
+    matches = {
+        i1: [_match(g1, "X", current=2.00, regular=2.00, is_on_sale=False)],
+        i2: [_match(g2, "Y", current=3.00, regular=3.00, is_on_sale=False)],
+    }
+    result = compute_recipe_cost(
+        recipe_id=recipe_id,
+        ingredients=[_ingredient(i1), _ingredient(i2)],
+        match_index=matches,
+        pantry_ingredient_ids={i1},
+    )
+    assert result.pantry_hit_count == 1
+    assert result.pantry_hit_pct == 0.5