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

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.WithBackOff 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.WithBackOff

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:ef21ba7dc538a01ebb4c0160df1a0ebe29801ef4c12221cd0dd15b2a3910f2e2","contract":["WithBackOff configures a custom BackOff strategy for Retry that supplies retry delays","WithBackOff resets the provided BackOff strategy before starting retries","WithBackOff halts retries when the BackOff strategy returns backoff.Stop","WithBackOff supports custom BackOff implementations with deterministic retry intervals","WithBackOff configures NewExponentialBackOff for operations that succeed within retry limits"],"goal":"verify github.com/cenkalti/backoff/v5.WithBackOff 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.WithBackOff"]},"contractCommand":["go","run","./test"],"environment":{"arch":"amd64","compiler":"go","compilerVersion":"1.26.6","distro":"ubuntu","ecosystem":"golang","language":"go","languageVersion":"1.26.6","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.WithBackOff"],"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
	operation := func() (string, error) {
		attempts++
		if attempts < 3 {
			return "", errors.New("temporary error")
		}
		return "success", nil
	}

	result, err := backoff.Retry(
		context.Background(),
		operation,
		backoff.WithBackOff(&backoff.ZeroBackOff{}),
	)
	if err != nil {
		fmt.Printf("retry failed: %v\n", err)
		return
	}

	fmt.Printf("operation succeeded after %d attempts: %s\n", attempts, result)
}

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

package main

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

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

// trackingBackOff records calls to Reset and NextBackOff for testing.
type trackingBackOff struct {
	resetCalled    int
	nextCalled     int
	delays         []time.Duration
	returnStopWhen int
}

func (t *trackingBackOff) Reset() {
	t.resetCalled++
}

func (t *trackingBackOff) NextBackOff() time.Duration {
	t.nextCalled++
	if t.returnStopWhen > 0 && t.nextCalled >= t.returnStopWhen {
		return backoff.Stop
	}
	if len(t.delays) > 0 {
		d := t.delays[0]
		t.delays = t.delays[1:]
		return d
	}
	return 0
}

func main() {
	ctx := context.Background()

	// Assertion 1: WithBackOff configures a custom BackOff strategy for Retry that supplies retry delays
	{
		attempts := 0
		op := func() (int, error) {
			attempts++
			if attempts < 3 {
				return 0, errors.New("temporary failure")
			}
			return 42, nil
		}

		res, err := backoff.Retry(
			ctx,
			op,
			backoff.WithBackOff(&backoff.ZeroBackOff{}),
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if res != 42 || attempts != 3 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected res=42 and attempts=3, got res=%d, attempts=%d\n", res, attempts)
			os.Exit(1)
		}
	}

	// Assertion 2: WithBackOff resets the provided BackOff strategy before starting retries
	{
		tracker := &trackingBackOff{}
		op := func() (string, error) {
			return "ready", nil
		}

		res, err := backoff.Retry(
			ctx,
			op,
			backoff.WithBackOff(tracker),
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if res != "ready" || tracker.resetCalled != 1 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected resetCalled=1, got %d\n", tracker.resetCalled)
			os.Exit(1)
		}
	}

	// Assertion 3: WithBackOff halts retries when the BackOff strategy returns backoff.Stop
	{
		attempts := 0
		expectedErr := errors.New("fatal transient error")
		op := func() (int, error) {
			attempts++
			return 0, expectedErr
		}

		_, err := backoff.Retry(
			ctx,
			op,
			backoff.WithBackOff(&backoff.StopBackOff{}),
		)
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected error, got nil\n")
			os.Exit(1)
		}
		if !errors.Is(err, expectedErr) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if attempts != 1 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected exactly 1 attempt with StopBackOff, got %d\n", attempts)
			os.Exit(1)
		}
	}

	// Assertion 4: WithBackOff supports custom BackOff implementations with deterministic retry intervals
	{
		tracker := &trackingBackOff{
			delays: []time.Duration{0, 0, 0},
		}
		attempts := 0
		op := func() (string, error) {
			attempts++
			if attempts < 4 {
				return "", errors.New("transient error")
			}
			return "custom success", nil
		}

		res, err := backoff.Retry(
			ctx,
			op,
			backoff.WithBackOff(tracker),
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if res != "custom success" || tracker.nextCalled != 3 || attempts != 4 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected nextCalled=3 and attempts=4, got next=%d, attempts=%d\n", tracker.nextCalled, attempts)
			os.Exit(1)
		}
	}

	// Assertion 5: WithBackOff configures NewExponentialBackOff for operations that succeed within retry limits
	{
		attempts := 0
		op := func() (bool, error) {
			attempts++
			if attempts < 2 {
				return false, errors.New("brief network glitch")
			}
			return true, nil
		}

		b := backoff.NewExponentialBackOff()
		b.InitialInterval = time.Millisecond

		res, err := backoff.Retry(
			ctx,
			op,
			backoff.WithBackOff(b),
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if !res || attempts != 2 {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected res=true and attempts=2, got res=%v, attempts=%d\n", res, attempts)
			os.Exit(1)
		}
	}

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