Add early fail for get_normal_newell when the provided polygon is t…

…oo small (< 3)

cjio/geom_help.py

@@ -35,6 +35,9 @@ def get_normal_newell(poly):
     n = np.array([0.0, 0.0, 0.0], dtype=np.float64)
     # if len(poly) == 0:
     #     print ("NOPOINTS")
+    if len(poly) < 3:
+        return n, False
+
     for i,p in enumerate(poly):
         ne = i + 1
         if (ne == len(poly)):

tests/test_geom_help.py

@@ -0,0 +1,57 @@
+import typing as t
+
+import numpy as np
+import numpy.typing as npt
+import pytest
+
+from cjio.geom_help import get_normal_newell
+
+
+@pytest.mark.parametrize(
+    ["poly", "expected_normal"],
+    [
+        (
+            [
+                [2195013, 353200, 12283],
+                [2195013, 353200, 8680],
+                [2182302, 347931, 8680],
+                [2182302, 347931, 12159],
+                [2182302, 347931, 12178],
+            ],
+            np.array([-0.38292729, 0.92377848, 0.0]),
+        ),
+        (
+            [
+                [2203406, 332904, 12622],
+                [2203406, 332904, 8680],
+                [2204954, 333543, 8680],
+                [2204954, 333543, 12223],
+                [2204954, 333543, 12584],
+            ],
+            np.array([0.38156054, -0.92434385, 0.0]),
+        ),
+    ],
+)
+def test_get_normal_valid_poly(poly: t.List[t.List[int]], expected_normal: npt.NDArray[t.Any]) -> None:
+    normal, success = get_normal_newell(poly=poly)
+    assert success
+    np.testing.assert_almost_equal(actual=normal, desired=expected_normal)
+
+
+@pytest.mark.parametrize(
+    ["poly", "expected_normal"],
+    [
+        (
+            [[1041, 1009, 1025, 1054, 1087]],
+            np.array([0.0, 0.0, 0.0]),
+        ),
+        (
+            [[[1099, 1098]]],
+            np.array([0.0, 0.0, 0.0]),
+        ),
+    ],
+)
+def test_get_normal_invalid_poly(poly: t.List[t.List[int]], expected_normal: npt.NDArray[t.Any]) -> None:
+    normal, success = get_normal_newell(poly=poly)
+    assert not success
+    np.testing.assert_almost_equal(actual=normal, desired=expected_normal)