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: repl_test.go
    path of file: ./repos/juju/cmd/juju/commands
    
    the code of the file until where you have to start completion: // Copyright 2020 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package commands

import (
	"bytes"
	"os/exec"
	"strings"

	"github.com/juju/cmd/v3"
	"github.com/juju/cmd/v3/cmdtesting"
	"github.com/juju/errors"
	"github.com/juju/loggo"
	jujutesting "github.com/juju/testing"
	jc "github.com/juju/testing/checkers"
	gc "gopkg.in/check.v1"

	"github.com/juju/juju/cmd/modelcmd"
	"github.com/juju/juju/jujuclient"
	"github.com/juju/juju/testin
    
func (s *ReplSuite) assertHelp(c *gc.C, helpArg string) {
	f := func() {
		// The jujuMain command is not designed to be run multiple times
		// in a loop as it attempts to register the same writer thus
		// causing an error to be returned and the actual command not
		// to execute.
		//
		// This is needed for testing only.
		_, _ = loggo.RemoveWriter("warning")
		jujuMain{
			execCommand: func(command string, args ...string) *exec.Cmd {
				c.Fail()
				return nil
			},
		}.Run([]string{"juju", helpArg})
	}

	stdout, _ := jujutesting.CaptureOutput(c, f)
	s.assertOutMatches(c, stdout,
		".*When run without arguments, Juju will enter an interactive shell.*")
}