github.com/spf13/pflag v1.0.10: ContinueOnError

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/spf13/pflag.ContinueOnError in pkg:golang/github.com/spf13/pflag@v1.0.10
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/spf13/pflag@v1.0.10
Demonstrate these symbols/APIs:
  - github.com/spf13/pflag.ContinueOnError

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:f4ecc9c6f07636a95d813d379e5d668c73162934c3380883a3d220359983b01b","contract":["NewFlagSet with ContinueOnError returns an error on unknown flag instead of exiting or panicking","NewFlagSet with ContinueOnError returns ErrHelp when --help flag is parsed without custom help definition","NewFlagSet with ContinueOnError returns an error on invalid flag value without exiting or panicking","NewFlagSet with ContinueOnError parses valid flags successfully returning nil error"],"goal":"verify github.com/spf13/pflag.ContinueOnError in pkg:golang/github.com/spf13/pflag@v1.0.10","kind":"HOW","packages":["pkg:golang/github.com/spf13/pflag@v1.0.10"],"schemaVersion":1,"symbols":["github.com/spf13/pflag.ContinueOnError"]},"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/spf13/pflag@v1.0.10"],"schemaVersion":1,"subject":"pkg:golang/github.com/spf13/pflag@v1.0.10","symbols":["github.com/spf13/pflag.ContinueOnError"],"verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/spf13/pflag v1.0.10

github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=

package main

import (
	"errors"
	"fmt"
	"os"

	"github.com/spf13/pflag"
)

func parseConfig(args []string) (string, int, error) {
	flags := pflag.NewFlagSet("app", pflag.ContinueOnError)
	name := flags.StringP("name", "n", "default", "User name")
	port := flags.IntP("port", "p", 8080, "Port number")

	if err := flags.Parse(args); err != nil {
		return "", 0, err
	}
	return *name, *port, nil
}

func main() {
	name, port, err := parseConfig(os.Args[1:])
	if err != nil {
		if errors.Is(err, pflag.ErrHelp) {
			os.Exit(0)
		}
		fmt.Fprintf(os.Stderr, "parse error: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Config: name=%s, port=%d\n", name, port)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/spf13/pflag.ContinueOnError in pkg:golang/github.com/spf13/pflag@v1.0.10",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/spf13/pflag@v1.0.10"
  ],
  "symbols": [
    "github.com/spf13/pflag.ContinueOnError"
  ]
}

package main

import (
	"errors"
	"fmt"
	"os"

	"github.com/spf13/pflag"
)

func main() {
	// 1. Unknown flag returns an error instead of exiting or panicking
	{
		flags := pflag.NewFlagSet("contract-unknown", pflag.ContinueOnError)
		flags.String("host", "localhost", "hostname")
		err := flags.Parse([]string{"--invalid-flag"})
		if err == nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected error on unknown flag, got nil\n")
			os.Exit(1)
		}
	}

	// 2. Undefined help flag returns pflag.ErrHelp instead of exiting
	{
		flags := pflag.NewFlagSet("contract-help", pflag.ContinueOnError)
		flags.String("host", "localhost", "hostname")
		err := flags.Parse([]string{"--help"})
		if !errors.Is(err, pflag.ErrHelp) {
			fmt.Fprintf(os.Stderr, "FAIL: expected ErrHelp on --help, got %v\n", err)
			os.Exit(1)
		}
	}

	// 3. Invalid flag value returns error instead of exiting or panicking
	{
		flags := pflag.NewFlagSet("contract-invalid", pflag.ContinueOnError)
		flags.Int("port", 8080, "port number")
		err := flags.Parse([]string{"--port=not-an-int"})
		if err == nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected error on invalid int flag value, got nil\n")
			os.Exit(1)
		}
	}

	// 4. Valid flags parse successfully and return nil error
	{
		flags := pflag.NewFlagSet("contract-valid", pflag.ContinueOnError)
		host := flags.String("host", "localhost", "hostname")
		port := flags.Int("port", 8080, "port number")
		verbose := flags.BoolP("verbose", "v", false, "verbose mode")

		err := flags.Parse([]string{"--host=example.com", "--port=9000", "-v"})
		if err != nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected nil error on valid flags, got %v\n", err)
			os.Exit(1)
		}
		if *host != "example.com" || *port != 9000 || !*verbose {
			fmt.Fprintf(os.Stderr, "FAIL: parsed flag values mismatch: host=%s, port=%d, verbose=%v\n", *host, *port, *verbose)
			os.Exit(1)
		}
	}

	fmt.Println("PASS: all contract assertions passed")
}