github.com/cenkalti/backoff/v5 v5.0.3: StopBackOff

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/cenkalti/backoff/v5.StopBackOff in pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3
Demonstrate these symbols/APIs:
  - github.com/cenkalti/backoff/v5.StopBackOff

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:f744243579e548ad6cfbdb554f7600c8c14bf44f4b7619b9660860c73ede9c78","contract":["StopBackOff implements the BackOff interface","StopBackOff.NextBackOff returns backoff.Stop across consecutive calls","StopBackOff.Reset can be called without altering NextBackOff behavior","Retry with StopBackOff executes only once and returns the error without retrying","Retry with StopBackOff returns the operation result when the initial attempt succeeds","NewTicker with StopBackOff delivers exactly one initial tick before closing"],"goal":"verify github.com/cenkalti/backoff/v5.StopBackOff in pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3","kind":"HOW","packages":["pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3"],"schemaVersion":1,"symbols":["github.com/cenkalti/backoff/v5.StopBackOff"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3"],"schemaVersion":1,"subject":"pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3","symbols":["github.com/cenkalti/backoff/v5.StopBackOff"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/cenkalti/backoff/v5 v5.0.3

github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=
github.com/cenkalti/backoff/v5 v5.0.3/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=

package main

import (
	"context"
	"errors"
	"fmt"

	"github.com/cenkalti/backoff/v5"
)

func main() {
	sb := &backoff.StopBackOff{}

	attempts := 0
	res, err := backoff.Retry(
		context.Background(),
		func() (string, error) {
			attempts++
			return "", errors.New("transient error")
		},
		backoff.WithBackOff(sb),
	)

	if err != nil {
		fmt.Printf("Retry stopped immediately after %d attempt(s): %v\n", attempts, err)
	} else {
		fmt.Printf("Result: %s\n", res)
	}

	fmt.Printf("StopBackOff NextBackOff returns sentinel: %v\n", sb.NextBackOff())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/cenkalti/backoff/v5.StopBackOff in pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/cenkalti/backoff/v5@v5.0.3"
  ],
  "symbols": [
    "github.com/cenkalti/backoff/v5.StopBackOff"
  ]
}

package main

import (
	"context"
	"errors"
	"fmt"
	"os"

	"github.com/cenkalti/backoff/v5"
)

func main() {
	// Assertion 1: StopBackOff implements the BackOff interface
	{
		var _ backoff.BackOff = (*backoff.StopBackOff)(nil)
		var b backoff.BackOff = &backoff.StopBackOff{}
		if d := b.NextBackOff(); d != backoff.Stop {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: BackOff interface call returned %v, expected %v\n", d, backoff.Stop)
			os.Exit(1)
		}
	}

	// Assertion 2: StopBackOff.NextBackOff returns backoff.Stop across consecutive calls
	{
		sb := &backoff.StopBackOff{}
		for i := 0; i < 5; i++ {
			if d := sb.NextBackOff(); d != backoff.Stop {
				fmt.Fprintf(os.Stderr, "assertion 2 failed: expected NextBackOff to return backoff.Stop, got %v\n", d)
				os.Exit(1)
			}
		}
	}

	// Assertion 3: StopBackOff.Reset can be called without altering NextBackOff behavior
	{
		sb := &backoff.StopBackOff{}
		sb.Reset()
		if d := sb.NextBackOff(); d != backoff.Stop {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected backoff.Stop after Reset, got %v\n", d)
			os.Exit(1)
		}
	}

	// Assertion 4: Retry with StopBackOff executes only once and returns the error without retrying
	{
		sb := &backoff.StopBackOff{}
		attempts := 0
		targetErr := errors.New("expected failure")
		_, err := backoff.Retry(
			context.Background(),
			func() (string, error) {
				attempts++
				return "", targetErr
			},
			backoff.WithBackOff(sb),
		)
		if !errors.Is(err, targetErr) {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected targetErr, got %v\n", err)
			os.Exit(1)
		}
		if attempts != 1 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected exactly 1 attempt, got %d\n", attempts)
			os.Exit(1)
		}
	}

	// Assertion 5: Retry with StopBackOff returns the operation result when the initial attempt succeeds
	{
		sb := &backoff.StopBackOff{}
		attempts := 0
		res, err := backoff.Retry(
			context.Background(),
			func() (string, error) {
				attempts++
				return "success", nil
			},
			backoff.WithBackOff(sb),
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if res != "success" || attempts != 1 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected res='success' and attempts=1, got res='%s', attempts=%d\n", res, attempts)
			os.Exit(1)
		}
	}

	// Assertion 6: NewTicker with StopBackOff delivers exactly one initial tick before closing
	{
		sb := &backoff.StopBackOff{}
		ticker := backoff.NewTicker(sb)
		ticks := 0
		for range ticker.C {
			ticks++
		}
		if ticks != 1 {
			fmt.Fprintf(os.Stderr, "assertion 6 failed: expected 1 tick before Stop, got %d\n", ticks)
			os.Exit(1)
		}
	}

	fmt.Println("All contract assertions passed successfully.")
}