worldgen: initial public history

1 files changed, 98 insertions, 0 deletions

diff --git a/tests/test_ice_fields.py b/tests/test_ice_fields.py
new file mode 100644
index 0000000..08fda18
--- /dev/null
+++ b/tests/test_ice_fields.py
@@ -0,0 +1,98 @@
+import unittest
+
+import numpy as np
+
+from mapgen import fields as FI
+from mapgen import ice as IC
+from tests.helpers import make_ctx
+
+
+class IceTest(unittest.TestCase):
+    def test_sheet_glacier_sea_ice(self):
+        ctx = make_ctx(3)
+        g = ctx.grid
+        polar_land = g.lat > 70
+        z = np.where(polar_land, 500.0, -3000.0)
+        peak = g.cell_index(0.0, 0.0)
+        z[peak] = 6000.0
+        t_mean = np.where(g.lat > 60, -25.0, 15.0)
+        t_mean[peak] = -9.0          # too warm for a sheet, summer below zero → glacier
+        t_sum = t_mean + 8
+        t_win = t_mean - 8
+        ctx.data.update({"elevation_eroded_m": z, "T_mean": t_mean, "T_jun": t_sum, "T_dec": t_win,
+                         "P_ann": np.full(g.n, 300.0)})
+        out = IC.run(ctx)
+        self.assertEqual(out["ice"][g.cell_index(85.0, 0.0)], IC.ICE_SHEET)
+        self.assertEqual(out["ice"][peak], IC.ICE_GLACIER)
+        self.assertEqual(out["ice"][g.cell_index(65.0, 0.0)], IC.ICE_SEA_PERENNIAL)
+        self.assertEqual(out["ice"][g.cell_index(0.0, 150.0)], IC.ICE_NONE)
+        i = g.cell_index(85.0, 0.0)
+        self.assertGreater(out["z_surface_m"][i], z[i] + 200)
+
+
+class FieldsTest(unittest.TestCase):
+    def test_o2_and_gravity(self):
+        ctx = make_ctx(1)
+        n = ctx.grid.n
+        zs = np.zeros(n)
+        zs[1] = 8000.0
+        m_o2 = np.zeros(n)
+        m_o2[2] = 1.0
+        m_g = np.zeros(n)
+        m_g[3] = -1.0
+        ctx.data.update({"z_surface_m": zs, "m_o2_zones": m_o2, "m_gravity_zones": m_g})
+        out = FI.run(ctx)
+        self.assertAlmostEqual(out["po2_bar"][0], 0.21)
+        self.assertAlmostEqual(out["po2_bar"][1], 0.21 * np.exp(-1), places=6)
+        self.assertAlmostEqual(out["po2_bar"][2], 0.21 * 1.5)
+        self.assertAlmostEqual(out["gravity_g"][0], 1.05)
+        self.assertAlmostEqual(out["gravity_g"][3], 1.05 * 0.3)
+
+    def test_pressure_o2_fraction_and_fire(self):
+        ctx = make_ctx(1)
+        n = ctx.grid.n
+        zs = np.zeros(n)
+        zs[1] = 8000.0
+        m_o2 = np.zeros(n)
+        m_o2[2] = 1.0
+        ctx.data.update({"z_surface_m": zs, "m_o2_zones": m_o2, "m_gravity_zones": np.zeros(n)})
+        out = FI.run(ctx)
+        self.assertAlmostEqual(out["pressure_bar"][0], 1.0)
+        self.assertAlmostEqual(out["pressure_bar"][1], np.exp(-1))
+        self.assertAlmostEqual(out["o2_fraction"][2], 0.21 * 1.5)
+        np.testing.assert_allclose(out["po2_bar"], out["o2_fraction"] * out["pressure_bar"])
+        self.assertTrue(np.all(out["fire_reactivity"] == 1.0))
+        np.testing.assert_allclose(out["plant_height_x"], ctx.cfg["planet"]["gravity_g"] / out["gravity_g"])
+        np.testing.assert_allclose(FI.pressure(2.0, np.array([-100.0, 8000.0]), 8000.0), [2.0, 2.0 * np.exp(-1)])
+
+class IceOceanMaskTest(unittest.TestCase):
+    def test_cold_inland_basin_is_not_sea_ice(self):
+        ctx = make_ctx(3)
+        g = ctx.grid
+        land = g.lat > 50
+        z = np.where(land, 300.0, -3000.0)
+        basin = (g.lat > 60) & (g.lat < 68) & (np.abs(g.lon) < 20)
+        z[basin] = -20.0
+        t = np.where(g.lat > 50, -5.0, 10.0)
+        ctx.data.update({"elevation_eroded_m": z, "ocean": ~land, "T_mean": t, "T_jun": t + 8, "T_dec": t - 8,
+                         "P_ann": np.full(g.n, 300.0)})
+        out = IC.run(ctx)
+        self.assertFalse(np.isin(out["ice"][basin], [IC.ICE_SEA_SEASONAL, IC.ICE_SEA_PERENNIAL]).any())
+
+
+class SummerMeltRuleTest(unittest.TestCase):
+    def test_ice_sheets_need_summers_below_freezing(self):
+        ctx = make_ctx(3)
+        g = ctx.grid
+        land = g.lat > 55
+        z = np.where(land, 300.0, -3000.0)
+        t_mean = np.where(g.lat > 75, -25.0, -12.0)           # 55–75°: cold on average, but summers melt
+        t_sum = np.where(g.lat > 75, -8.0, 4.0)
+        peak = g.cell_index(0.0, 0.0)
+        z[peak], t_mean[peak], t_sum[peak] = 6000.0, -9.0, -1.0
+        ctx.data.update({"elevation_eroded_m": z, "ocean": ~(land | (np.arange(g.n) == peak)), "T_mean": t_mean,
+                         "T_jun": t_sum, "T_dec": t_mean - 10, "P_ann": np.full(g.n, 300.0)})
+        out = IC.run(ctx)
+        self.assertEqual(out["ice"][g.cell_index(65.0, 0.0)], IC.ICE_NONE)        # tundra, not ice
+        self.assertEqual(out["ice"][g.cell_index(85.0, 0.0)], IC.ICE_SHEET)
+        self.assertEqual(out["ice"][peak], IC.ICE_GLACIER)                          # small cold spot = glacier