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: modelwatcher.go
    path of file: ./repos/juju/apiserver/common/testing
    
    the code of the file until where you have to start completion: // Copyright 2014 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package testing

import (
	jc "github.com/juju/testing/checkers"
	gc "gopkg.in/check.v1"

	"github.com/juju/juju/apiserver/common"
	"github.com/juju/juju/rpc/params"
	"github.com/juju/juju/state"
	statetesting "github.com/juju/juju/state/testing"
)

type ModelWatcher interface {
	WatchForModelConfigChanges() (params.NotifyWatchResult, error)
	ModelConfig() (params.Mode
    
func (s *ModelWatcherTest) TestWatchForModelConfigChanges(c *gc.C) {
	c.Assert(s.res.Count(), gc.Equals, 0)

	result, err := s.modelWatcher.WatchForModelConfigChanges()
	c.Assert(err, jc.ErrorIsNil)
	c.Assert(result, gc.DeepEquals, params.NotifyWatchResult{
		NotifyWatcherId: "1",
	})

	// Verify the resources were registered and stop them when done.
	c.Assert(s.res.Count(), gc.Equals, 1)
	resource := s.res.Get("1")
	defer statetesting.AssertStop(c, resource)

	// Check that the Watch has consumed the initial event ("returned"
	// in the Watch call)
	wc := statetesting.NewNotifyWatcherC(c, resource.(state.NotifyWatcher))
	wc.AssertNoChange()
}