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

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.ZeroBackOff 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.ZeroBackOff

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:sha256:9a3d1be6f4922ab926260f6b4e272897b145a92021e655e9c46c51800dc2b446","contract":["ZeroBackOff.NextBackOff returns zero duration across consecutive calls","ZeroBackOff.Reset can be called without altering NextBackOff behavior","ZeroBackOff implements the BackOff interface","Retry with ZeroBackOff immediately retries and succeeds upon eventual success","Retry with ZeroBackOff and WithMaxTries ceases retries when errors persist"],"goal":"verify github.com/cenkalti/backoff/v5.ZeroBackOff 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.ZeroBackOff"]},"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.ZeroBackOff"],"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() {
	b := &backoff.ZeroBackOff{}

	attempts := 0
	res, err := backoff.Retry(
		context.Background(),
		func() (string, error) {
			attempts++
			if attempts < 3 {
				return "", errors.New("transient failure")
			}
			return "success", nil
		},
		backoff.WithBackOff(b),
		backoff.WithMaxTries(5),
	)

	if err != nil {
		fmt.Printf("Retry failed: %v\n", err)
		return
	}

	fmt.Printf("Result: %s after %d attempts (next backoff: %v)\n", res, attempts, b.NextBackOff())
}

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

package main

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

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

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

	// Assertion 2: ZeroBackOff.Reset can be called without altering NextBackOff behavior
	{
		zb := &backoff.ZeroBackOff{}
		zb.Reset()
		if d := zb.NextBackOff(); d != 0 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 0 after Reset, got %v\n", d)
			os.Exit(1)
		}
	}

	// Assertion 3: ZeroBackOff implements the BackOff interface
	{
		var _ backoff.BackOff = (*backoff.ZeroBackOff)(nil)
		var b backoff.BackOff = &backoff.ZeroBackOff{}
		if d := b.NextBackOff(); d != 0 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: BackOff interface call returned %v\n", d)
			os.Exit(1)
		}
	}

	// Assertion 4: Retry with ZeroBackOff immediately retries and succeeds upon eventual success
	{
		zb := &backoff.ZeroBackOff{}
		attempts := 0
		start := time.Now()
		res, err := backoff.Retry(
			context.Background(),
			func() (string, error) {
				attempts++
				if attempts < 3 {
					return "", errors.New("temporary error")
				}
				return "ok", nil
			},
			backoff.WithBackOff(zb),
		)
		elapsed := time.Since(start)
		if err != nil || res != "ok" || attempts != 3 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: err=%v, res=%s, attempts=%d\n", err, res, attempts)
			os.Exit(1)
		}
		if elapsed > 500*time.Millisecond {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: ZeroBackOff took unexpectedly long (%v)\n", elapsed)
			os.Exit(1)
		}
	}

	// Assertion 5: Retry with ZeroBackOff and WithMaxTries ceases retries when errors persist
	{
		zb := &backoff.ZeroBackOff{}
		attempts := 0
		expectedErr := errors.New("persistent failure")
		_, err := backoff.Retry(
			context.Background(),
			func() (struct{}, error) {
				attempts++
				return struct{}{}, expectedErr
			},
			backoff.WithBackOff(zb),
			backoff.WithMaxTries(4),
		)
		if err == nil || attempts != 4 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected error and 4 attempts, got err=%v, attempts=%d\n", err, attempts)
			os.Exit(1)
		}
	}

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