feat: AR-ElecArrangement initial commit — Python FastAPI + uvicorn (LAN desktop app, packaged as .exe via PyInstaller)

backend/tests/test_units.py

@@ -0,0 +1,65 @@
+"""
+Sprint 0 — sanity: conversiones SI ↔ imperial round-trip y casos límite.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from arelec.core.units import (
+    AWG_TO_MM2,
+    awg_to_mm2,
+    ft_to_m,
+    kg_to_lb,
+    kw_to_hp,
+    lb_to_kg,
+    m_to_ft,
+    mm2_to_awg,
+    hp_to_kw,
+)
+
+
+def test_length_roundtrip() -> None:
+    assert m_to_ft(1.0) == pytest.approx(3.28084, rel=1e-4)
+    assert ft_to_m(m_to_ft(42.0)) == pytest.approx(42.0)
+
+
+def test_mass_roundtrip() -> None:
+    assert kg_to_lb(1.0) == pytest.approx(2.20462, rel=1e-4)
+    assert lb_to_kg(kg_to_lb(100.0)) == pytest.approx(100.0)
+
+
+def test_power_roundtrip() -> None:
+    assert hp_to_kw(1.0) == pytest.approx(0.7355)
+    assert kw_to_hp(hp_to_kw(150.0)) == pytest.approx(150.0)
+
+
+def test_awg_lookup_known_values() -> None:
+    # ABYC E-11 tabla VI — valores publicados estándar
+    assert awg_to_mm2("10") == 5.26
+    assert awg_to_mm2("4/0") == 107.0
+    assert awg_to_mm2("14") == 2.08
+
+
+def test_mm2_to_awg_picks_next_larger() -> None:
+    # 5.0 mm² no es exactamente AWG 10 (5.26), pero AWG 10 cubre el cable.
+    # Criterio conservador: elegir AWG cuya área es ≥ pedida.
+    assert mm2_to_awg(5.0) == "10"
+    assert mm2_to_awg(5.26) == "10"
+    assert mm2_to_awg(2.0) == "14"   # 2.08
+    assert mm2_to_awg(100.0) == "4/0"  # 107
+
+
+def test_mm2_to_awg_rejects_invalid() -> None:
+    with pytest.raises(ValueError):
+        mm2_to_awg(0)
+    with pytest.raises(ValueError):
+        mm2_to_awg(-1.0)
+    with pytest.raises(ValueError):
+        mm2_to_awg(500.0)  # más grande que 4/0
+
+
+def test_awg_table_monotonic() -> None:
+    """La tabla AWG debe ir de menor a mayor área (asumido por mm2_to_awg)."""
+    areas = list(AWG_TO_MM2.values())
+    assert areas == sorted(areas)