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

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.Stop 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.Stop

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:sha256:23b2ba56fc95a3ba15034826274d0c30d1e11f2342af02651fbea4004de0dd71","contract":["backoff.Stop is a sentinel duration constant equal to -1 representing no more retries","StopBackOff returns backoff.Stop from NextBackOff across consecutive calls and after Reset","Retry halts retrying immediately and returns the operation error when NextBackOff returns backoff.Stop","custom BackOff policy returning backoff.Stop after a limit ceases retries without further attempts","NewTicker stops and closes its channel when BackOff returns backoff.Stop"],"goal":"verify github.com/cenkalti/backoff/v5.Stop 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.Stop"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","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.Stop"],"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() {
	attempts := 0
	res, err := backoff.Retry(
		context.Background(),
		func() (string, error) {
			attempts++
			return "", errors.New("operation failed")
		},
		backoff.WithBackOff(&backoff.StopBackOff{}),
	)

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

	fmt.Printf("Stop duration constant: %v\n", backoff.Stop)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/cenkalti/backoff/v5.Stop 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.Stop"
  ]
}

package main

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

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

type customStepBackOff struct {
	attempts int
	maxSteps int
}

func (c *customStepBackOff) Reset() {
	c.attempts = 0
}

func (c *customStepBackOff) NextBackOff() time.Duration {
	if c.attempts >= c.maxSteps {
		return backoff.Stop
	}
	c.attempts++
	return 0
}

func main() {
	// Assertion 1: backoff.Stop is a sentinel duration constant equal to -1 representing no more retries
	{
		if backoff.Stop != -1 || backoff.Stop != time.Duration(-1) {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected backoff.Stop to equal -1, got %v\n", backoff.Stop)
			os.Exit(1)
		}
	}

	// Assertion 2: StopBackOff returns backoff.Stop from NextBackOff across consecutive calls and after Reset
	{
		sb := &backoff.StopBackOff{}
		for i := 0; i < 3; 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)
			}
		}
		sb.Reset()
		if d := sb.NextBackOff(); d != backoff.Stop {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected backoff.Stop after Reset, got %v\n", d)
			os.Exit(1)
		}
	}

	// Assertion 3: Retry halts retrying immediately and returns the operation error when NextBackOff returns backoff.Stop
	{
		sb := &backoff.StopBackOff{}
		attempts := 0
		targetErr := errors.New("immediate stop error")
		_, err := backoff.Retry(
			context.Background(),
			func() (struct{}, error) {
				attempts++
				return struct{}{}, targetErr
			},
			backoff.WithBackOff(sb),
		)
		if !errors.Is(err, targetErr) || attempts != 1 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected targetErr and 1 attempt, got err=%v, attempts=%d\n", err, attempts)
			os.Exit(1)
		}
	}

	// Assertion 4: custom BackOff policy returning backoff.Stop after a limit ceases retries without further attempts
	{
		b := &customStepBackOff{maxSteps: 3}
		attempts := 0
		retryErr := errors.New("intermittent failure")
		_, err := backoff.Retry(
			context.Background(),
			func() (string, error) {
				attempts++
				return "", retryErr
			},
			backoff.WithBackOff(b),
		)
		// Initial attempt (1) + 3 retries = 4 attempts total
		if !errors.Is(err, retryErr) || attempts != 4 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected retryErr and 4 attempts, got err=%v, attempts=%d\n", err, attempts)
			os.Exit(1)
		}
	}

	// Assertion 5: NewTicker stops and closes its channel when BackOff returns backoff.Stop
	{
		sb := &backoff.StopBackOff{}
		ticker := backoff.NewTicker(sb)
		ticks := 0
		for range ticker.C {
			ticks++
		}
		if ticks != 1 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected 1 tick before Stop, got %d\n", ticks)
			os.Exit(1)
		}
	}

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