def test07a_polygons(self):
        "Testing Polygon objects."

        # Testing `from_bbox` class method
        bbox = (-180, -90, 180, 90)
        p = OGRGeometry.from_bbox(bbox)
        self.assertEqual(bbox, p.extent)

        prev = OGRGeometry('POINT(0 0)')
        for p in self.geometries.polygons:
            poly = OGRGeometry(p.wkt)
            self.assertEqual(3, poly.geom_type)
            self.assertEqual('POLYGON', poly.geom_name)
            self.assertEqual(p.n_p, poly.point_count)
            self.assertEqual(p.n_i + 1, len(poly))

            # Testing area & centroid.
            self.assertAlmostEqual(p.area, poly.area, 9)
            x, y = poly.centroid.tuple
            self.assertAlmostEqual(p.centroid[0], x, 9)
            self.assertAlmostEqual(p.centroid[1], y, 9)

            # Testing equivalence
            self.assertEqual(True, poly == OGRGeometry(p.wkt))
            self.assertEqual(True, poly != prev)

            if p.ext_ring_cs:
                ring = poly[0]
                self.assertEqual(p.ext_ring_cs, ring.tuple)
                self.assertEqual(p.ext_ring_cs, poly[0].tuple)
                self.assertEqual(len(p.ext_ring_cs), ring.point_count)

            for r in poly:
                self.assertEqual('LINEARRING', r.geom_name)
    def test06_spatial_filter(self):
        "Testing the Layer.spatial_filter property."
        ds = DataSource(get_ds_file('cities', 'shp'))
        lyr = ds[0]

        # When not set, it should be None.
        self.assertEqual(None, lyr.spatial_filter)

        # Must be set a/an OGRGeometry or 4-tuple.
        self.assertRaises(TypeError, lyr._set_spatial_filter, 'foo')

        # Setting the spatial filter with a tuple/list with the extent of
        # a buffer centering around Pueblo.
        self.assertRaises(ValueError, lyr._set_spatial_filter, range(5))
        filter_extent = (-105.609252, 37.255001, -103.609252, 39.255001)
        lyr.spatial_filter = (-105.609252, 37.255001, -103.609252, 39.255001)
        self.assertEqual(OGRGeometry.from_bbox(filter_extent),
                         lyr.spatial_filter)
        feats = [feat for feat in lyr]
        self.assertEqual(1, len(feats))
        self.assertEqual('Pueblo', feats[0].get('Name'))

        # Setting the spatial filter with an OGRGeometry for buffer centering
        # around Houston.
        filter_geom = OGRGeometry(
            'POLYGON((-96.363151 28.763374,-94.363151 28.763374,-94.363151 30.763374,-96.363151 30.763374,-96.363151 28.763374))'
        )
        lyr.spatial_filter = filter_geom
        self.assertEqual(filter_geom, lyr.spatial_filter)
        feats = [feat for feat in lyr]
        self.assertEqual(1, len(feats))
        self.assertEqual('Houston', feats[0].get('Name'))

        # Clearing the spatial filter by setting it to None.  Now
        # should indicate that there are 3 features in the Layer.
        lyr.spatial_filter = None
        self.assertEqual(3, len(lyr))