grass.pygrass: Raise GrassError in c_read_next_line when Vect_read_next_line fails

python/grass/pygrass/vector/geometry.py

@@ -1888,7 +1888,8 @@ def c_read_next_line(c_mapinfo, c_points, c_cats):
     if ftype == -2:
         raise StopIteration
     if ftype == -1:
-        raise
+        msg = "Cannot read the next line"
+        raise GrassError(msg)
     return ftype, v_id, c_points, c_cats
 
 

python/grass/pygrass/vector/testsuite/test_geometry.py

@@ -5,15 +5,17 @@
 """
 
 import unittest
+from unittest.mock import MagicMock, patch
 
 import numpy as np
 
 import grass.lib.vector as libvect
+from grass.exceptions import GrassError
 from grass.gunittest.case import TestCase
 from grass.gunittest.main import test
 from grass.pygrass.vector import VectorTopo
 from grass.pygrass.vector.basic import Bbox
-from grass.pygrass.vector.geometry import Area, Line, Node, Point
+from grass.pygrass.vector.geometry import Area, Line, Node, Point, c_read_next_line
 
 
 class PointTestCase(TestCase):
@@ -390,5 +392,33 @@ def test_isles_2(self):
         self.assertEqual(str(isle.bbox()), "Bbox(3.0, 1.0, 3.0, 1.0)")
 
 
+class ReadNextLineTestCase(TestCase):
+    def test_c_read_next_line_error(self):
+        """Test c_read_next_line raises GrassError when Vect_read_next_line returns -1"""
+        mock_mapinfo = MagicMock()
+        mock_mapinfo.contents.next_line = 1
+        with (
+            patch(
+                "grass.pygrass.vector.geometry.libvect.Vect_read_next_line",
+                return_value=-1,
+            ),
+            self.assertRaises(GrassError),
+        ):
+            c_read_next_line(mock_mapinfo, None, None)
+
+    def test_c_read_next_line_stop_iteration(self):
+        """Test c_read_next_line raises StopIteration when Vect_read_next_line returns -2"""
+        mock_mapinfo = MagicMock()
+        mock_mapinfo.contents.next_line = 1
+        with (
+            patch(
+                "grass.pygrass.vector.geometry.libvect.Vect_read_next_line",
+                return_value=-2,
+            ),
+            self.assertRaises(StopIteration),
+        ):
+            c_read_next_line(mock_mapinfo, None, None)
+
+
 if __name__ == "__main__":
     test()