test: add DCF and valuation backend tests

1 files changed, 126 insertions, 0 deletions

diff --git a/backend/tests/test_valuation_advanced_endpoint.py b/backend/tests/test_valuation_advanced_endpoint.py
new file mode 100644
index 0000000..3cdb857
--- /dev/null
+++ b/backend/tests/test_valuation_advanced_endpoint.py
@@ -0,0 +1,126 @@
+import pandas as pd
+import pytest
+from fastapi.testclient import TestClient
+
+from app import main
+from app.services import data_service
+
+
+def annual_frame(rows: dict[str, list[float]]) -> pd.DataFrame:
+    columns = pd.to_datetime(["2024-09-30", "2023-09-30", "2022-09-30", "2021-09-30"])
+    return pd.DataFrame(rows, index=columns).T
+
+
+def quarterly_frame(rows: dict[str, list[float]]) -> pd.DataFrame:
+    columns = pd.to_datetime(["2025-12-31", "2025-09-30", "2025-06-30", "2025-03-31"])
+    return pd.DataFrame(rows, index=columns).T
+
+
+def clear_valuation_cache() -> None:
+    data_service.VALUATION_CACHE.clear()
+
+
+def advanced_payload() -> dict[str, float | int | list[float]]:
+    return {
+        "base_revenue": 1_000.0,
+        "revenue_growth": [0.10, 0.05],
+        "ebitda_margin": [0.30, 0.32],
+        "dna_pct_revenue": [0.05, 0.05],
+        "capex_pct_revenue": [0.07, 0.07],
+        "nwc_chg_pct_delta_rev": [0.02, 0.02],
+        "tax_rate": [0.25, 0.25],
+        "wacc": 0.10,
+        "terminal_growth": 0.03,
+        "projection_years": 2,
+    }
+
+
+def test_simple_valuation_includes_five_by_five_sensitivity_grid(monkeypatch: pytest.MonkeyPatch) -> None:
+    # Given: historical free cash flow data for the simple DCF endpoint.
+    clear_valuation_cache()
+    cash_flow = annual_frame({
+        "Operating Cash Flow": [100.0, 90.0, 80.0, 70.0],
+        "Capital Expenditure": [-10.0, -9.0, -8.0, -7.0],
+    })
+    monkeypatch.setattr(data_service, "get_cash_flow", lambda symbol, quarterly=False: pd.DataFrame() if quarterly else cash_flow)
+    monkeypatch.setattr(data_service, "get_income_statement", lambda symbol, quarterly=False: pd.DataFrame())
+    monkeypatch.setattr(data_service, "get_balance_sheet", lambda symbol, quarterly=False: pd.DataFrame())
+    monkeypatch.setattr(data_service, "get_company_info", lambda symbol: {"currentPrice": 150.0})
+    monkeypatch.setattr(data_service, "get_shares_outstanding", lambda symbol: 1_000_000_000.0)
+
+    # When: the simple valuation service is called.
+    result = data_service.get_valuation("ref")
+
+    # Then: the DCF result includes the mandated WACC x terminal-growth matrix.
+    dcf = result["dcf"]
+    sensitivity = dcf["sensitivity"]
+    assert result["currency"] == "USD"
+    assert result["currency_warning"] is None
+    assert sensitivity["wacc"] == [0.08, 0.09, 0.10, 0.11, 0.12]
+    assert sensitivity["terminal_growth"] == [0.015, 0.02, 0.03, 0.04, 0.045]
+    assert len(sensitivity["implied_prices"]) == 5
+    assert all(len(row) == 5 for row in sensitivity["implied_prices"])
+    assert sensitivity["implied_prices"][2][2] == pytest.approx(dcf["intrinsic_value_per_share"])
+
+
+def test_advanced_valuation_endpoint_returns_inputs_and_sensitivity(monkeypatch: pytest.MonkeyPatch) -> None:
+    # Given: symbol-level balance sheet inputs and a base valuation shell.
+    clear_valuation_cache()
+    monkeypatch.setattr(
+        data_service,
+        "get_valuation",
+        lambda symbol: {
+            "symbol": "REF",
+            "current_price": 42.0,
+            "shares_outstanding": 100.0,
+            "dcf": {"available": False, "wacc": 0.10, "terminal_growth": 0.03, "projection_years": 5},
+            "ev_ebitda": {"available": False},
+            "ev_revenue": {"available": False},
+            "price_to_book": {"available": False},
+        },
+    )
+    monkeypatch.setattr(data_service, "get_shares_outstanding", lambda symbol: 100.0)
+    monkeypatch.setattr(
+        data_service,
+        "get_balance_sheet",
+        lambda symbol, quarterly=False: quarterly_frame({
+            "Total Debt": [50.0, 0.0, 0.0, 0.0],
+            "Cash And Cash Equivalents": [10.0, 0.0, 0.0, 0.0],
+            "Preferred Stock": [5.0, 0.0, 0.0, 0.0],
+            "Minority Interest": [3.0, 0.0, 0.0, 0.0],
+        }),
+    )
+    client = TestClient(main.app)
+
+    # When: the advanced valuation endpoint receives an explicit build payload.
+    response = client.post("/api/tickers/REF/valuation/advanced", json=advanced_payload())
+
+    # Then: it returns a full valuation response with base-case-centered sensitivity.
+    assert response.status_code == 200
+    body = response.json()
+    dcf = body["dcf"]
+    sensitivity = dcf["sensitivity"]
+    assert body["symbol"] == "REF"
+    assert body["currency"] == "USD"
+    assert body["currency_warning"] is None
+    assert dcf["advanced_inputs"] == advanced_payload()
+    assert dcf["intrinsic_value_per_share"] == pytest.approx(29.838067203890013)
+    assert sensitivity["wacc"] == [0.08, 0.09, 0.10, 0.11, 0.12]
+    assert sensitivity["terminal_growth"] == [0.015, 0.02, 0.03, 0.04, 0.045]
+    assert len(sensitivity["implied_prices"]) == 5
+    assert all(len(row) == 5 for row in sensitivity["implied_prices"])
+    assert sensitivity["implied_prices"][2][2] == pytest.approx(dcf["intrinsic_value_per_share"])
+
+
+def test_advanced_valuation_endpoint_rejects_short_projection_arrays() -> None:
+    # Given: a payload whose per-year arrays do not cover projection_years.
+    payload = advanced_payload()
+    payload["revenue_growth"] = [0.10]
+    client = TestClient(main.app)
+
+    # When: the invalid payload is submitted.
+    response = client.post("/api/tickers/REF/valuation/advanced", json=payload)
+
+    # Then: FastAPI returns a validation response instead of an unhandled exception.
+    assert response.status_code == 422
+    assert "projection_years" in response.text