Fixed #25663 -- Added checking of the number of points for LinearRing and LineString.

django/contrib/gis/geos/linestring.py

@@ -36,16 +36,24 @@ class LineString(ProjectInterpolateMixin, GEOSGeometry):
             # Getting the number of coords and the number of dimensions -- which
             #  must stay the same, e.g., no LineString((1, 2), (1, 2, 3)).
             ncoords = len(coords)
-            if coords:
-                ndim = len(coords[0])
-            else:
-                raise TypeError('Cannot initialize on empty sequence.')
-            self._checkdim(ndim)
+            if ncoords < self._minlength:
+                raise TypeError(
+                    '%s requires at least %d points, got %s.' % (
+                        self.__class__.__name__,
+                        self._minlength,
+                        ncoords,
+                    )
+                )
+            ndim = None
             # Incrementing through each of the coordinates and verifying
-            for i in range(1, ncoords):
-                if not isinstance(coords[i], (tuple, list, Point)):
-                    raise TypeError('each coordinate should be a sequence (list or tuple)')
-                if len(coords[i]) != ndim:
+            for coord in coords:
+                if not isinstance(coord, (tuple, list, Point)):
+                    raise TypeError('Each coordinate should be a sequence (list or tuple)')
+
+                if ndim is None:
+                    ndim = len(coord)
+                    self._checkdim(ndim)
+                elif len(coord) != ndim:
                     raise TypeError('Dimension mismatch.')
             numpy_coords = False
         elif numpy and isinstance(coords, numpy.ndarray):

tests/gis_tests/geos_tests/test_geos.py

@@ -3,7 +3,6 @@ from __future__ import unicode_literals
 import ctypes
 import json
 import random
-import unittest
 from binascii import a2b_hex, b2a_hex
 from io import BytesIO
 from unittest import skipUnless
@@ -19,7 +18,7 @@ from django.contrib.gis.geos.base import GEOSBase
 from django.contrib.gis.shortcuts import numpy
 from django.template import Context
 from django.template.engine import Engine
-from django.test import ignore_warnings, mock
+from django.test import SimpleTestCase, ignore_warnings, mock
 from django.utils import six
 from django.utils.deprecation import RemovedInDjango20Warning
 from django.utils.encoding import force_bytes
@@ -29,7 +28,7 @@ from ..test_data import TestDataMixin
 
 
 @skipUnless(HAS_GEOS, "Geos is required.")
-class GEOSTest(unittest.TestCase, TestDataMixin):
+class GEOSTest(SimpleTestCase, TestDataMixin):
 
     def test_base(self):
         "Tests out the GEOSBase class."
@@ -326,6 +325,12 @@ class GEOSTest(unittest.TestCase, TestDataMixin):
             if numpy:
                 self.assertEqual(ls, LineString(numpy.array(ls.tuple)))  # as numpy array
 
+            with self.assertRaisesMessage(TypeError, 'Each coordinate should be a sequence (list or tuple)'):
+                LineString((0, 0))
+
+            with self.assertRaisesMessage(TypeError, 'LineString requires at least 2 points, got 1.'):
+                LineString([(0, 0)])
+
     def test_multilinestring(self):
         "Testing MultiLineString objects."
         prev = fromstr('POINT(0 0)')
@@ -369,6 +374,12 @@ class GEOSTest(unittest.TestCase, TestDataMixin):
             if numpy:
                 self.assertEqual(lr, LinearRing(numpy.array(lr.tuple)))
 
+        with self.assertRaisesMessage(TypeError, 'LinearRing requires at least 4 points, got 3.'):
+            LinearRing((0, 0), (1, 1), (0, 0))
+
+        with self.assertRaisesMessage(TypeError, 'LinearRing requires at least 4 points, got 1.'):
+            LinearRing([(0, 0)])
+
     def test_polygons_from_bbox(self):
         "Testing `from_bbox` class method."
         bbox = (-180, -90, 180, 90)