def test_get_segment_by_id(self):
        segment = {api.NETWORK_TYPE: "vlan", api.PHYSICAL_NETWORK: "physnet1", api.SEGMENTATION_ID: 1}

        net_segment = self._create_segments([segment])[0]
        segment_uuid = net_segment[api.ID]

        net_segment = ml2_db.get_segment_by_id(self.ctx.session, segment_uuid)
        self.assertEqual(segment, net_segment)

    def test_delete_network_segment(self):
        segment = {api.NETWORK_TYPE: "vlan", api.PHYSICAL_NETWORK: "physnet1", api.SEGMENTATION_ID: 1}

        net_segment = self._create_segments([segment])[0]
        segment_uuid = net_segment[api.ID]

        ml2_db.delete_network_segment(self.ctx.session, segment_uuid)
        # Get segment and verify its empty
        net_segment = ml2_db.get_segment_by_id(self.ctx.session, segment_uuid)
        self.assertIsNone(net_segment)

 def release_dynamic_segment(self, session, segment_id):
     """Delete a dynamic segment."""
     segment = db.get_segment_by_id(session, segment_id)
     if segment:
         driver = self.drivers.get(segment.get(api.NETWORK_TYPE))
         if driver:
             driver.obj.release_segment(session, segment)
             db.delete_network_segment(session, segment_id)
         else:
             LOG.error(_LE("Failed to release segment '%s' because " "network type is not supported."), segment)
     else:
         LOG.debug("No segment found with id %(segment_id)s", segment_id)

 def test_get_segment_by_id_result_not_found(self):
     segment_uuid = uuidutils.generate_uuid()
     net_segment = ml2_db.get_segment_by_id(self.ctx.session, segment_uuid)
     self.assertIsNone(net_segment)

 def _expand_segment(self, segment_id):
     segment = db.get_segment_by_id(self._plugin_context.session,
                                    segment_id)
     if not segment:
         LOG.warning(_LW("Could not expand segment %s"), segment_id)
     return segment