Improved messages in IndexErrors raised by GDAL objects.

django/contrib/gis/gdal/datasource.py

@@ -89,12 +89,12 @@ class DataSource(GDALBase):
         if isinstance(index, str):
             layer = capi.get_layer_by_name(self.ptr, force_bytes(index))
             if not layer:
-                raise IndexError('invalid OGR Layer name given: "%s"' % index)
+                raise IndexError('Invalid OGR layer name given: %s.' % index)
         elif isinstance(index, int):
             if 0 <= index < self.layer_count:
                 layer = capi.get_layer(self._ptr, index)
             else:
-                raise IndexError('index out of range')
+                raise IndexError('Index out of range when accessing layers in a datasource: %s.' % index)
         else:
             raise TypeError('Invalid index type: %s' % type(index))
         return Layer(layer, self)

django/contrib/gis/gdal/feature.py

@@ -38,7 +38,7 @@ class Feature(GDALBase):
         elif 0 <= index < self.num_fields:
             i = index
         else:
-            raise IndexError('index out of range')
+            raise IndexError('Index out of range when accessing field in a feature: %s.' % index)
         return Field(self, i)
 
     def __len__(self):
@@ -111,5 +111,5 @@ class Feature(GDALBase):
         "Return the index of the given field name."
         i = capi.get_field_index(self.ptr, force_bytes(field_name))
         if i < 0:
-            raise IndexError('invalid OFT field name given: "%s"' % field_name)
+            raise IndexError('Invalid OFT field name given: %s.' % field_name)
         return i

django/contrib/gis/gdal/geometries.py

@@ -564,7 +564,7 @@ class LineString(OGRGeometry):
             elif dim == 3:
                 return (x.value, y.value, z.value)
         else:
-            raise IndexError('index out of range: %s' % index)
+            raise IndexError('Index out of range when accessing points of a line string: %s.' % index)
 
     def __len__(self):
         "Return the number of points in the LineString."
@@ -616,7 +616,7 @@ class Polygon(OGRGeometry):
         if 0 <= index < self.geom_count:
             return OGRGeometry(capi.clone_geom(capi.get_geom_ref(self.ptr, index)), self.srs)
         else:
-            raise IndexError('index out of range: %s' % index)
+            raise IndexError('Index out of range when accessing rings of a polygon: %s.' % index)
 
     # Polygon Properties
     @property
@@ -655,7 +655,7 @@ class GeometryCollection(OGRGeometry):
         if 0 <= index < self.geom_count:
             return OGRGeometry(capi.clone_geom(capi.get_geom_ref(self.ptr, index)), self.srs)
         else:
-            raise IndexError('index out of range: %s' % index)
+            raise IndexError('Index out of range when accessing geometry in a collection: %s.' % index)
 
     def __len__(self):
         "Return the number of geometries in this Geometry Collection."

tests/gis_tests/gdal_tests/test_ds.py

 import os
 import re
-import unittest
 
 from django.contrib.gis.gdal import (
     GDAL_VERSION, DataSource, Envelope, GDALException, OGRGeometry,
 )
 from django.contrib.gis.gdal.field import OFTInteger, OFTReal, OFTString
+from django.test import SimpleTestCase
 
 from ..test_data import TEST_DATA, TestDS, get_ds_file
 
@@ -64,7 +64,7 @@ ds_list = (
 bad_ds = (TestDS('foo'),)
 
 
-class DataSourceTest(unittest.TestCase):
+class DataSourceTest(SimpleTestCase):
 
     def test01_valid_shp(self):
         "Testing valid SHP Data Source files."
@@ -83,11 +83,12 @@ class DataSourceTest(unittest.TestCase):
             self.assertEqual(source.driver, str(ds.driver))
 
             # Making sure indexing works
-            with self.assertRaises(IndexError):
-                ds[len(ds)]
+            msg = 'Index out of range when accessing layers in a datasource: %s.'
+            with self.assertRaisesMessage(IndexError, msg % len(ds)):
+                ds.__getitem__(len(ds))
 
-            with self.assertRaises(IndexError):
-                ds['invalid']
+            with self.assertRaisesMessage(IndexError, 'Invalid OGR layer name given: invalid.'):
+                ds.__getitem__('invalid')
 
     def test02_invalid_shp(self):
         "Testing invalid SHP files for the Data Source."
@@ -122,9 +123,9 @@ class DataSourceTest(unittest.TestCase):
                     self.assertIn(f, source.fields)
 
                 # Negative FIDs are not allowed.
-                with self.assertRaises(IndexError):
+                with self.assertRaisesMessage(IndexError, 'Negative indices are not allowed on OGR Layers.'):
                     layer.__getitem__(-1)
-                with self.assertRaises(IndexError):
+                with self.assertRaisesMessage(IndexError, 'Invalid feature id: 50000.'):
                     layer.__getitem__(50000)
 
                 if hasattr(source, 'field_values'):
@@ -141,6 +142,13 @@ class DataSourceTest(unittest.TestCase):
                         for fld_name, fld_value in source.field_values.items():
                             self.assertEqual(fld_value[i], feat.get(fld_name))
 
+                        msg = 'Index out of range when accessing field in a feature: %s.'
+                        with self.assertRaisesMessage(IndexError, msg % len(feat)):
+                            feat.__getitem__(len(feat))
+
+                        with self.assertRaisesMessage(IndexError, 'Invalid OFT field name given: invalid.'):
+                            feat.__getitem__('invalid')
+
     def test03b_layer_slice(self):
         "Test indexing and slicing on Layers."
         # Using the first data-source because the same slice

tests/gis_tests/gdal_tests/test_geom.py

 import json
 import pickle
-import unittest
 from binascii import b2a_hex
 
 from django.contrib.gis.gdal import (
@@ -8,11 +7,12 @@ from django.contrib.gis.gdal import (
 )
 from django.template import Context
 from django.template.engine import Engine
+from django.test import SimpleTestCase
 
 from ..test_data import TestDataMixin
 
 
-class OGRGeomTest(unittest.TestCase, TestDataMixin):
+class OGRGeomTest(SimpleTestCase, TestDataMixin):
     "This tests the OGR Geometry."
 
     def test_geomtype(self):
@@ -158,7 +158,8 @@ class OGRGeomTest(unittest.TestCase, TestDataMixin):
             self.assertEqual(ls.coords, linestr.tuple)
             self.assertEqual(linestr, OGRGeometry(ls.wkt))
             self.assertNotEqual(linestr, prev)
-            with self.assertRaises(IndexError):
+            msg = 'Index out of range when accessing points of a line string: %s.'
+            with self.assertRaisesMessage(IndexError, msg % len(linestr)):
                 linestr.__getitem__(len(linestr))
             prev = linestr
 
@@ -183,7 +184,8 @@ class OGRGeomTest(unittest.TestCase, TestDataMixin):
             for ls in mlinestr:
                 self.assertEqual(2, ls.geom_type)
                 self.assertEqual('LINESTRING', ls.geom_name)
-            with self.assertRaises(IndexError):
+            msg = 'Index out of range when accessing geometry in a collection: %s.'
+            with self.assertRaisesMessage(IndexError, msg % len(mlinestr)):
                 mlinestr.__getitem__(len(mlinestr))
 
     def test_linearring(self):
@@ -213,6 +215,9 @@ class OGRGeomTest(unittest.TestCase, TestDataMixin):
             self.assertEqual('POLYGON', poly.geom_name)
             self.assertEqual(p.n_p, poly.point_count)
             self.assertEqual(p.n_i + 1, len(poly))
+            msg = 'Index out of range when accessing rings of a polygon: %s.'
+            with self.assertRaisesMessage(IndexError, msg % len(poly)):
+                poly.__getitem__(len(poly))
 
             # Testing area & centroid.
             self.assertAlmostEqual(p.area, poly.area, 9)
@@ -263,7 +268,8 @@ class OGRGeomTest(unittest.TestCase, TestDataMixin):
             if mp.valid:
                 self.assertEqual(mp.n_p, mpoly.point_count)
                 self.assertEqual(mp.num_geom, len(mpoly))
-                with self.assertRaises(IndexError):
+                msg = 'Index out of range when accessing geometry in a collection: %s.'
+                with self.assertRaisesMessage(IndexError, msg % len(mpoly)):
                     mpoly.__getitem__(len(mpoly))
                 for p in mpoly:
                     self.assertEqual('POLYGON', p.geom_name)