118 lines
3.6 KiB
Python
118 lines
3.6 KiB
Python
"""Business case maths + exports."""
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from __future__ import annotations
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import pytest
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from tokencalc.business_case import build_business_case, npv, payback_years
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from tokencalc.defaults import (
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CTM_DEFAULT_FEATURE_SCOPES,
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CTM_DEFAULT_SITES,
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CTM_DEFAULT_TAKEOUTS,
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DEFAULT_METERS,
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DEFAULT_PRICING,
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)
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from tokencalc.exports import (
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export_excel,
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scenario_state_from_json,
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scenario_state_to_json,
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)
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def test_npv_hand_check():
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"""100/yr for 3 years @ 8%: 92.593 + 85.734 + 79.383 = 257.710."""
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assert npv([100, 100, 100], 0.08) == pytest.approx(257.710, abs=0.001)
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def test_payback_interpolation():
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# -100 in Y1, +200 in Y2 → breakeven halfway through Y2 = 1.5 years
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assert payback_years([-100, 200, 0]) == pytest.approx(1.5)
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assert payback_years([-100, -100, -100]) is None
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assert payback_years([50, 50, 50]) == pytest.approx(0.0)
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def _case(scenario="realistic", **kw):
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return build_business_case(
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CTM_DEFAULT_SITES, CTM_DEFAULT_FEATURE_SCOPES, DEFAULT_METERS,
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DEFAULT_PRICING, CTM_DEFAULT_TAKEOUTS, scenario, **kw,
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)
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def test_business_case_shape():
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case = _case()
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assert set(case) == {
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"cost_by_year", "benefit_by_year", "takeouts_by_year",
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"net_by_year", "cumulative_net", "npv",
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"payback_period_years", "roi_3yr",
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}
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for key in ("cost_by_year", "benefit_by_year", "net_by_year"):
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assert {"Y1", "Y2", "Y3"} <= set(case[key].columns)
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def test_net_consistency():
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"""NET row must equal benefits + takeouts − costs, per year."""
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case = _case()
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nb = case["net_by_year"].set_index("line")
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for y in ("Y1", "Y2", "Y3"):
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assert nb.loc["NET", y] == pytest.approx(
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nb.loc["TOTAL BENEFITS", y]
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+ nb.loc["TOTAL TAKEOUTS", y]
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- nb.loc["TOTAL COSTS", y]
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)
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# cumulative is a running sum of NET
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assert nb.loc["Cumulative net", "Y3"] == pytest.approx(
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sum(nb.loc["NET", y] for y in ("Y1", "Y2", "Y3"))
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)
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def test_npv_matches_net_rows():
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case = _case()
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nb = case["net_by_year"].set_index("line")
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net = [nb.loc["NET", y] for y in ("Y1", "Y2", "Y3")]
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assert case["npv"] == pytest.approx(npv(net, 0.08))
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def test_three_scenarios_distinct():
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npvs = {s: _case(s)["npv"] for s in ("floor", "realistic", "stretch")}
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assert len({round(v) for v in npvs.values()}) == 3
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assert npvs["floor"] < npvs["realistic"] < npvs["stretch"]
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def test_implementation_amortization():
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base = _case()
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with_impl = _case(implementation_cost=900_000)
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nb, nb2 = (
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c["net_by_year"].set_index("line") for c in (base, with_impl)
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)
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for y in ("Y1", "Y2", "Y3"):
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assert nb2.loc["TOTAL COSTS", y] == pytest.approx(
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nb.loc["TOTAL COSTS", y] + 300_000
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)
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def test_excel_export_readable(tmp_path):
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case = _case()
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path = export_excel(
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{
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"Business Case": case["net_by_year"],
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"Costs": case["cost_by_year"],
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"Benefits": case["benefit_by_year"],
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},
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tmp_path / "ctm.xlsx",
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)
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import openpyxl
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wb = openpyxl.load_workbook(path)
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assert set(wb.sheetnames) == {"Business Case", "Costs", "Benefits"}
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def test_scenario_json_roundtrip(tmp_path):
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p = tmp_path / "state.json"
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scenario_state_to_json(
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CTM_DEFAULT_SITES, CTM_DEFAULT_TAKEOUTS, CTM_DEFAULT_FEATURE_SCOPES, p
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)
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sites, takeouts, scopes, _rollout = scenario_state_from_json(p)
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assert [s.site_name for s in sites] == [s.site_name for s in CTM_DEFAULT_SITES]
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assert takeouts[0].annual_cost == CTM_DEFAULT_TAKEOUTS[0].annual_cost
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assert scopes[0].adoption_curve == CTM_DEFAULT_FEATURE_SCOPES[0].adoption_curve
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