Model/tests/domain/modelling/test_overlay_applicator.py

"""Behaviour of the Overlay Applicator: folding Simulation Overlays
(EpcSimulation) onto a baseline EpcPropertyData to produce a new one for
the calculator. See ADR-0016 and the Modelling glossary in CONTEXT.md.
"""

from datatypes.epc.domain.epc_property_data import (
    BuildingPartIdentifier,
    EpcPropertyData,
    SapBuildingPart,
    SapVentilation,
)
from domain.modelling.simulation import (
    BuildingPartOverlay,
    EpcSimulation,
    VentilationOverlay,
)
from domain.modelling.scoring.overlay_applicator import apply_simulations
from tests.domain.sap10_calculator.worksheet._elmhurst_worksheet_000490 import (
    build_epc,
)


def _part(epc: EpcPropertyData, identifier: BuildingPartIdentifier) -> SapBuildingPart:
    return next(p for p in epc.sap_building_parts if p.identifier is identifier)


def test_apply_writes_targeted_building_part_and_leaves_others_untouched() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()
    extension_before: int | str = _part(
        baseline, BuildingPartIdentifier.EXTENSION_1
    ).wall_insulation_type
    simulation = EpcSimulation(
        building_parts={
            BuildingPartIdentifier.MAIN: BuildingPartOverlay(wall_insulation_type=1)
        }
    )

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [simulation])

    # Assert
    assert _part(result, BuildingPartIdentifier.MAIN).wall_insulation_type == 1
    assert (
        _part(result, BuildingPartIdentifier.EXTENSION_1).wall_insulation_type
        == extension_before
    )


def test_empty_simulation_is_a_no_op() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [EpcSimulation()])

    # Assert
    assert result == baseline


def test_later_simulation_wins_on_a_shared_field() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()
    first = EpcSimulation(
        building_parts={
            BuildingPartIdentifier.MAIN: BuildingPartOverlay(wall_insulation_type=1)
        }
    )
    second = EpcSimulation(
        building_parts={
            BuildingPartIdentifier.MAIN: BuildingPartOverlay(wall_insulation_type=2)
        }
    )

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [first, second])

    # Assert
    assert _part(result, BuildingPartIdentifier.MAIN).wall_insulation_type == 2


def test_apply_writes_dwelling_ventilation_onto_sap_ventilation() -> None:
    # Arrange — a Measure Dependency overlay targets the whole-dwelling
    # ventilation system (no building part), e.g. retrofit MEV.
    baseline: EpcPropertyData = build_epc()
    simulation = EpcSimulation(
        ventilation=VentilationOverlay(
            mechanical_ventilation_kind="EXTRACT_OR_PIV_OUTSIDE"
        )
    )

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [simulation])

    # Assert
    assert result.sap_ventilation is not None
    assert (
        result.sap_ventilation.mechanical_ventilation_kind
        == "EXTRACT_OR_PIV_OUTSIDE"
    )


def test_ventilation_overlay_creates_sap_ventilation_when_baseline_has_none() -> None:
    # Arrange — a naturally-ventilated baseline that lodged no SapVentilation.
    baseline: EpcPropertyData = build_epc()
    baseline.sap_ventilation = None
    simulation = EpcSimulation(
        ventilation=VentilationOverlay(
            mechanical_ventilation_kind="EXTRACT_OR_PIV_OUTSIDE"
        )
    )

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [simulation])

    # Assert
    assert isinstance(result.sap_ventilation, SapVentilation)
    assert (
        result.sap_ventilation.mechanical_ventilation_kind
        == "EXTRACT_OR_PIV_OUTSIDE"
    )


def test_ventilation_overlay_leaves_building_parts_and_baseline_untouched() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()
    main_before: int | str = _part(
        baseline, BuildingPartIdentifier.MAIN
    ).wall_insulation_type
    simulation = EpcSimulation(
        ventilation=VentilationOverlay(
            mechanical_ventilation_kind="EXTRACT_OR_PIV_OUTSIDE"
        )
    )

    # Act
    result: EpcPropertyData = apply_simulations(baseline, [simulation])

    # Assert — ventilation overlay touches only sap_ventilation; the baseline
    # is never mutated.
    assert _part(result, BuildingPartIdentifier.MAIN).wall_insulation_type == main_before
    assert baseline.sap_ventilation is not None
    assert baseline.sap_ventilation.mechanical_ventilation_kind is None


def test_baseline_is_not_mutated() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()
    original: int | str = _part(
        baseline, BuildingPartIdentifier.MAIN
    ).wall_insulation_type

    # Act
    _: EpcPropertyData = apply_simulations(
        baseline,
        [
            EpcSimulation(
                building_parts={
                    BuildingPartIdentifier.MAIN: BuildingPartOverlay(
                        wall_insulation_type=1
                    )
                }
            )
        ],
    )

    # Assert
    assert (
        _part(baseline, BuildingPartIdentifier.MAIN).wall_insulation_type == original
    )