handling fixed cost exceeding our budget, creating negative budget

recommendations/Recommendations.py

@@ -1,7 +1,7 @@
 import pandas as pd
 import numpy as np
 from backend.Property import Property
-from typing import List, Mapping
+from typing import List, Mapping, Any
 from itertools import groupby
 from recommendations.FloorRecommendations import FloorRecommendations
 from recommendations.WallRecommendations import WallRecommendations
@@ -499,23 +499,26 @@ class Recommendations:
         return predicted_appliances_cost_reduction, predicted_appliances_kwh_reduction
 
     @staticmethod
-    def _check_veniltation_out_of_bounds(sap_impact, ventilation_sap_limit):
+    def _check_ventilation_out_of_bounds(sap_impact, ventilation_sap_limit):
         return (sap_impact < ventilation_sap_limit) or (sap_impact >= 0)
 
     @staticmethod
     def _adjust_ventilation_sap(sap_impact, ventilation_sap_limit):
+
         if sap_impact >= 0:
             return -1
         if sap_impact < ventilation_sap_limit:
             return ventilation_sap_limit
 
+        return sap_impact
+
     @staticmethod
     def _filter_phase_adjustment(phase_adjustments):
         """
         Utility function to select the entry from the dictionary, by phase, with the largest
         phase adjustment
         :param phase_adjustments: List of phase adjustments, in the form
-        [{"recommendation_id": str, "phase": int, "adjustment_amount": float}]
+        [{"recommendation_id": str, "phase": int, "sap_adjustment": float}]
         :return:
         """
         filtered_adjustments = []
@@ -583,6 +586,15 @@ class Recommendations:
         if len(previous_phase_reps) == 1:
             return previous_phase_reps[0]
 
+        # It's unlikely that this will occur but this fallback will ensure that we don't
+        # run the next step and run a median of nothing, which will return None
+        if not previous_phase_reps:
+            return {
+                "sap": float(property_instance.data["current-energy-efficiency"]),
+                "carbon": float(property_instance.data["co2-emissions-current"]),
+                "heat_demand": float(property_instance.data["energy-consumption-current"]),
+            }
+
         # Median fallback (including zero-length case)
         keys = ("sap", "carbon", "heat_demand")
         return {
@@ -612,9 +624,9 @@ class Recommendations:
     @classmethod
     def _resolve_current_phase_sap(
         cls,
-        rec: Mapping[str, any],
-        previous_phase_values: Mapping[str, any],
-        phase_energy_efficiency_metrics: Mapping[str, any],
+        rec: Mapping[str, Any],
+        previous_phase_values: Mapping[str, Any],
+        phase_energy_efficiency_metrics: Mapping[str, Any],
         adjustments: list[dict],
     ) -> float:
         if rec.get("survey", False):
@@ -713,14 +725,14 @@ class Recommendations:
         elif rec["type"] == "mechanical_ventilation":
             # ventilation is capped by having no greater and a -4 impact
             ventilation_sap_limit = -4
-            ventilation_out_of_bounds = cls._check_veniltation_out_of_bounds(
+            ventilation_out_of_bounds = cls._check_ventilation_out_of_bounds(
                 property_phase_impact["sap"], ventilation_sap_limit
             )
 
             if ventilation_out_of_bounds:
                 previous_modelled_sap = previous_phase_values.get("sap_prediction", 0)
                 proposed_sap_impact = current_phase_values["sap"] - previous_modelled_sap
-                proposal_out_of_bounds = cls._check_veniltation_out_of_bounds(
+                proposal_out_of_bounds = cls._check_ventilation_out_of_bounds(
                     proposed_sap_impact, ventilation_sap_limit
                 )
                 if proposal_out_of_bounds:
@@ -805,7 +817,7 @@ class Recommendations:
         return property_phase_impact, current_phase_values, adjustments
 
     @staticmethod
-    def _validate_recommendation_updates(rec: Mapping[str, any]):
+    def _validate_recommendation_updates(rec: Mapping[str, Any]):
         """
         Utility function to validate that the recommendation updates have been applied correctly
         :param rec: updated recommendation
@@ -821,11 +833,11 @@ class Recommendations:
     def calculate_recommendation_impact(
         cls,
         property_instance: Property,
-        all_predictions: Mapping[str, any],
+        all_predictions: Mapping[str, Any],
         recommendations: Mapping[int, List],
         representative_recommendations: Mapping[int, List],
         debug: bool = False
-    ) -> (Mapping[int, List], List[Mapping[str, any]]):
+    ) -> (Mapping[int, List], List[Mapping[str, Any]]):
 
         """
         Given predictions from the model apis, with method will update the recommendations with the predicted

recommendations/optimiser/funding_optimiser.py

@@ -711,9 +711,12 @@ def optimise_with_scenarios(
             if kept:
                 remaining_measures.append(kept)
 
+        remaining_budget = budget - fabric_cost if budget is not None else None
+        remaining_budget = 0 if remaining_budget < 0 else remaining_budget
+
         picked_extra, extra_cost, extra_gain = run_optimizer(
             remaining_measures,
-            budget=budget - fabric_cost if budget is not None else None,
+            budget=remaining_budget,
             sub_target_gain=(
                 target_gain - fabric_gain
                 if target_gain is not None
@@ -769,6 +772,12 @@ def optimise_with_scenarios(
 
         fixed_cost, fixed_gain = sum_cost_gain(fixed_items)
 
+        if budget is not None:
+            # If we have a budget, we cannot exceed it via our fixed cost. If we do,
+            # this is not a viable solution
+            if fixed_cost > budget:
+                continue
+
         # Remaining measures (all other groups)
         remaining_measures = [
             grp for gi, grp in enumerate(optimisation_measures)

recommendations/tests/test_recommendations.py

@@ -1,9 +1,6 @@
 import pytest
-import datetime
 import pandas as pd
 import numpy as np
-from pandas import Timestamp
-from numpy import nan
 from unittest.mock import Mock
 
 from recommendations.Recommendations import Recommendations
@@ -372,6 +369,153 @@ def test_filter_phase_adjustment(input_data, expected):
     assert Recommendations._filter_phase_adjustment(input_data) == expected
 
 
+@pytest.mark.parametrize(
+    "sap_impact, limit, expected",
+    [
+        (1.0, -4, True),  # positive SAP not allowed
+        (0.0, -4, True),  # zero not allowed
+        (-1.0, -4, False),  # valid range
+        (-3.9, -4, False),  # valid range
+        (-4.0, -4, False),  # exact lower bound allowed
+        (-4.1, -4, True),  # below lower bound
+    ],
+)
+def test_check_ventilation_out_of_bounds(sap_impact, limit, expected):
+    assert Recommendations._check_ventilation_out_of_bounds(
+        sap_impact, limit
+    ) is expected
+
+
+@pytest.mark.parametrize(
+    "sap_impact, limit, expected",
+    [
+        (1.2, -4, -1),  # positive → capped to -1
+        (0.0, -4, -1),  # zero → capped to -1
+        (-5.0, -4, -4),  # below limit → clamp
+        (-3.0, -4, -3.0),  # already valid → unchanged
+    ],
+)
+def test_adjust_ventilation_sap(sap_impact, limit, expected):
+    assert Recommendations._adjust_ventilation_sap(
+        sap_impact, limit
+    ) == expected
+
+
+def test_get_previous_phase_values_starting_phase(property_instance):
+    result = Recommendations._get_previous_phase_values(
+        rec_phase=0,
+        starting_phase=0,
+        impact_summary=[],
+        property_instance=property_instance,
+    )
+
+    assert result == {
+        "sap": 65.0,
+        "carbon": 2.4,
+        "heat_demand": 284.0,
+    }
+
+
+def test_get_previous_phase_values_single_rep(property_instance):
+    impact_summary = [
+        {
+            "phase": 0,
+            "representative": True,
+            "sap": 66,
+            "carbon": 2.2,
+            "heat_demand": 260,
+        }
+    ]
+
+    result = Recommendations._get_previous_phase_values(
+        rec_phase=1,
+        starting_phase=0,
+        impact_summary=impact_summary,
+        property_instance=property_instance,
+    )
+
+    assert result["sap"] == 66
+    assert result["carbon"] == 2.2
+    assert result["heat_demand"] == 260
+
+
+def test_get_previous_phase_values_median(property_instance):
+    impact_summary = [
+        {"phase": 1, "representative": True, "sap": 70, "carbon": 2.0, "heat_demand": 250},
+        {"phase": 1, "representative": True, "sap": 74, "carbon": 1.6, "heat_demand": 230},
+    ]
+
+    result = Recommendations._get_previous_phase_values(
+        rec_phase=2,
+        starting_phase=0,
+        impact_summary=impact_summary,
+        property_instance=property_instance,
+    )
+
+    assert result["sap"] == np.median([70, 74])
+    assert result["carbon"] == np.median([2.0, 1.6])
+    assert result["heat_demand"] == np.median([250, 230])
+
+
+def test_compute_phase_impact_standard():
+    previous = {"sap": 65, "carbon": 2.4, "heat_demand": 284}
+    current = {"sap": 64, "carbon": 2.6, "heat_demand": 300}
+
+    impact = Recommendations._compute_phase_impact(
+        rec_type="loft_insulation",
+        previous_phase_values=previous,
+        current_phase_values=current,
+    )
+
+    # monotonicity enforced
+    assert impact["sap"] == 0
+    assert impact["carbon"] == 0
+    assert impact["heat_demand"] == 0
+
+
+def test_compute_phase_impact_mechanical_ventilation():
+    previous = {"sap": 65, "carbon": 2.4, "heat_demand": 284}
+    current = {"sap": 63, "carbon": 2.4, "heat_demand": 284}
+
+    impact = Recommendations._compute_phase_impact(
+        rec_type="mechanical_ventilation",
+        previous_phase_values=previous,
+        current_phase_values=current,
+    )
+
+    assert impact["sap"] == -2
+
+
+def test_resolve_current_phase_sap_with_adjustments():
+    rec = {"phase": 3, "survey": False}
+    previous = {"sap": 65}
+    phase_metrics = {"sap_change": 70}
+    adjustments = [
+        {"phase": 1, "sap_adjustment": 1.5},
+        {"phase": 2, "sap_adjustment": 2.0},
+    ]
+
+    sap = Recommendations._resolve_current_phase_sap(
+        rec=rec,
+        previous_phase_values=previous,
+        phase_energy_efficiency_metrics=phase_metrics,
+        adjustments=adjustments,
+    )
+
+    assert sap == 70 - (1.5 + 2.0)
+
+
+def test_validate_recommendation_updates_raises():
+    rec = {
+        "sap_points": None,
+        "co2_equivalent_savings": None,
+        "heat_demand": None,
+    }
+
+    with pytest.raises(ValueError):
+        Recommendations._validate_recommendation_updates(rec)
+
+
 def test_calculate_recommendation_impact(property_instance, heat_demand_predictions, carbon_predictions):
     #######
     # Case 3

tox.ini

@@ -9,5 +9,5 @@ deps =
     -rbackend/engine/requirements.txt
     -rbackend/app/requirements/requirements.txt
     -rtest.requirements.txt
-commands = pytest
+commands = pytest {posargs}