You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: subnets_test.go
    path of file: ./repos/juju/apiserver/facades/client/subnets
    
    the code of the file until where you have to start completion: // Copyright 2015 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package subnets_test

import (
	"github.com/juju/collections/set"
	"github.com/juju/errors"
	"github.com/juju/names/v5"
	jc "github.com/juju/testing/checkers"
	"go.uber.org/mock/gomock"
	gc "gopkg.in/check.v1"

	"github.com/juju/juju/apiserver/common"
	"gith
    
func (s *SubnetsSuite) TestAllZonesWithNoBackingZonesAndSetFails(c *gc.C) {
	apiservertesting.BackingInstance.SetUp(c, apiservertesting.StubZonedEnvironName, apiservertesting.WithoutZones, apiservertesting.WithSpaces, apiservertesting.WithSubnets)
	apiservertesting.SharedStub.SetErrors(
		nil,                             // Backing.AvailabilityZones
		nil,                             // Backing.ModelConfig
		nil,                             // Backing.CloudSpec
		nil,                             // Provider.Open
		nil,                             // ZonedEnviron.AvailabilityZones
		errors.NotSupportedf("setting"), // Backing.SetAvailabilityZones
	)

	results, err := s.facade.AllZones()
	c.Assert(err, gc.ErrorMatches,
		`cannot update known zones: setting not supported`,
	)
	// Verify the cause is not obscured.
	c.Assert(err, jc.Satisfies, errors.IsNotSupported)
	c.Assert(results, jc.DeepEquals, params.ZoneResults{})

	apiservertesting.CheckMethodCalls(c, apiservertesting.SharedStub,
		apiservertesting.BackingCall("AvailabilityZones"),
		apiservertesting.BackingCall("ModelConfig"),
		apiservertesting.BackingCall("CloudSpec"),
		apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
		apiservertesting.ZonedEnvironCall("AvailabilityZones", s.callContext),
		apiservertesting.BackingCall("SetAvailabilityZones", apiservertesting.ProviderInstance.Zones),
	)
}