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: manta_test.go
    path of file: ./repos/vault/physical/manta
    
    the code of the file until where you have to start completion: // Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package manta

import (
	"context"
	"fmt"
	"math/rand"
	"os"
	"path"
	"testing"
	"time"

	log "github.com/hashicorp/go-hclog"
	"github.com/hashicorp/vault/sdk/helper/logging"
	"github.com/hashicorp/vault/sdk/physical"
	triton "github.com/joyent/triton-go"
	"github.com/joyent/triton-go/authentication"
	tt "github.com/joyent/triton-go/errors"
	"github.com/joyent/triton-go/storage"
)

func TestMantaBackend(t *testing.T) {
	user := os.Getenv("MANTA_USER")
	keyId := os.Getenv("MANTA_KEY_ID")
	url := "https://us-east.manta.joyent.com"
	testHarnessBucket := fmt.Sprintf("test-bucket-%d", randInt())

	if user == "" || keyId == "" {
		t.SkipNow()
	}

	input := authentication.SSHAgentSignerInput{
		KeyID:       keyId,
		AccountName: user,
		Username:    "",
	}
	signer, err := authentication.NewSSHAgentSigner(input)
	if err != nil {
		t.Fatalf("Error Creating SSH Agent Signer: %s", err.Error())
	}

	config := &triton.ClientConfig{
		MantaURL:    url,
		AccountName: user,
		Signers:     []authentication.Signer{signer},
	}

	client, err := storage.NewClient(config)
	if err != nil {
		t.Fatalf("failed initialising Storage client: %s", err.Error())
	}

	logger := logging.NewVaultLogger(log.Debug)
	mb := &MantaBackend{
		client:     client,
		directory:  testHarnessBucket,
		logger:     logg
    
func TestMantaBackend(t *testing.T) {
	user := os.Getenv("MANTA_USER")
	keyId := os.Getenv("MANTA_KEY_ID")
	url := "https://us-east.manta.joyent.com"
	testHarnessBucket := fmt.Sprintf("test-bucket-%d", randInt())

	if user == "" || keyId == "" {
		t.SkipNow()
	}

	input := authentication.SSHAgentSignerInput{
		KeyID:       keyId,
		AccountName: user,
		Username:    "",
	}
	signer, err := authentication.NewSSHAgentSigner(input)
	if err != nil {
		t.Fatalf("Error Creating SSH Agent Signer: %s", err.Error())
	}

	config := &triton.ClientConfig{
		MantaURL:    url,
		AccountName: user,
		Signers:     []authentication.Signer{signer},
	}

	client, err := storage.NewClient(config)
	if err != nil {
		t.Fatalf("failed initialising Storage client: %s", err.Error())
	}

	logger := logging.NewVaultLogger(log.Debug)
	mb := &MantaBackend{
		client:     client,
		directory:  testHarnessBucket,
		logger:     logger.Named("storage.mantabackend"),
		permitPool: physical.NewPermitPool(128),
	}

	err = mb.client.Dir().Put(context.Background(), &storage.PutDirectoryInput{
		DirectoryName: path.Join(mantaDefaultRootStore),
	})
	if err != nil {
		t.Fatal("Error creating test harness directory")
	}

	defer func() {
		err = mb.client.Dir().Delete(context.Background(), &storage.DeleteDirectoryInput{
			DirectoryName: path.Join(mantaDefaultRootStore, testHarnessBucket),
			ForceDelete:   true,
		})
		if err != nil {
			if !tt.IsResourceNotFoundError(err) {
				t.Fatal("failed to delete test harness directory")
			}
		}
	}()

	physical.ExerciseBackend(t, mb)
	physical.ExerciseBackend_ListPrefix(t, mb)
}