Removed some more hardcoded backends in GIS tests

    # Does the database contain a SpatialRefSys model to store SRID information?

    has_spatialrefsys_table = True

    # Reference implementation of 3D functions is:

    # http://postgis.net/docs/PostGIS_Special_Functions_Index.html#PostGIS_3D_Functions

    supports_3d_functions = False

    # Does the database support SRID transform operations?

    supports_transform = True

    # Do geometric relationship operations operate on real shapes (or only on bounding boxes)?

    # The following properties indicate if the database backend support

    # certain lookups (dwithin, left and right, relate, ...)

    supports_distances_lookups = True

    supports_left_right_lookups = False

    @property

    def supports_relate_lookup(self):

        return 'relate' in self.connection.ops.geometry_functions

    def supports_bbcontains_lookup(self):

        return 'bbcontains' in self.connection.ops.gis_terms

    @property

    def supports_contained_lookup(self):

        return 'contained' in self.connection.ops.gis_terms

    @property

    def has_dwithin_lookup(self):

    def supports_dwithin_lookup(self):

        return 'dwithin' in self.connection.ops.distance_functions

    @property

    def supports_relate_lookup(self):

        return 'relate' in self.connection.ops.gis_terms

    # For each of those methods, the class will have a property named

    # `has_<name>_method` (defined in __init__) which accesses connection.ops

    # to determine GIS method availability.

    geoqueryset_methods = (

        'centroid', 'difference', 'envelope', 'force_rhr', 'geohash', 'gml',

        'intersection', 'kml', 'num_geom', 'perimeter', 'point_on_surface',

        'reverse', 'scale', 'snap_to_grid', 'svg', 'sym_difference',

        'transform', 'translate', 'union', 'unionagg',

        'area', 'centroid', 'difference', 'distance', 'distance_spheroid',

        'envelope', 'force_rhr', 'geohash', 'gml', 'intersection', 'kml',

        'length', 'num_geom', 'perimeter', 'point_on_surface', 'reverse',

        'scale', 'snap_to_grid', 'svg', 'sym_difference', 'transform',

        'translate', 'union', 'unionagg',

    )

    # Specifies whether the Collect and Extent aggregates are supported by the database

class DatabaseFeatures(BaseSpatialFeatures, MySQLDatabaseFeatures):

    has_spatialrefsys_table = False

    supports_distances_lookups = False

    supports_transform = False

    supports_real_shape_operations = False

    supports_null_geometries = False

class DatabaseFeatures(BaseSpatialFeatures, Psycopg2DatabaseFeatures):

    supports_3d_functions = True

    supports_left_right_lookups = True

                u, unit_name, s = get_srid_info(self.query.transformed_srid, connection)

                geodetic = unit_name.lower() in geo_field.geodetic_units

            if backend.spatialite and geodetic:

                raise ValueError('SQLite does not support linear distance calculations on geodetic coordinate systems.')

            if geodetic and not connection.features.supports_distance_geodetic:

                raise ValueError('This database does not support linear distance calculations on geodetic coordinate systems.')

            if distance:

                if self.query.transformed_srid:

                    # works on 3D geometries.

                    procedure_fmt += ",'%(spheroid)s'"

                    procedure_args.update({'function': backend.length_spheroid, 'spheroid': params[1]})

                elif geom_3d and backend.postgis:

                    # Use 3D variants of perimeter and length routines on PostGIS.

                elif geom_3d and connection.features.supports_3d_functions:

                    # Use 3D variants of perimeter and length routines on supported backends.

                    if perimeter:

                        procedure_args.update({'function': backend.perimeter3d})

                    elif length:

from django.contrib.gis.db import models

from django.contrib.gis.tests.utils import gisfield_may_be_null

from django.utils.encoding import python_2_unicode_compatible

class SouthTexasZipcode(NamedModel):

    "Model for a few South Texas ZIP codes."

    poly = models.PolygonField(srid=32140, null=True)

    poly = models.PolygonField(srid=32140, null=gisfield_may_be_null)

class Interstate(NamedModel):