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

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.NewFlagSet 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.NewFlagSet

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:sha256:640c9f69ab1276188088d8a89eb3642931ff8920c09b8c8ee58a72daa39ee20b","contract":["pflag.NewFlagSet initializes a FlagSet that parses short and long flags with type conversions","pflag.NewFlagSet tracks changed flags, positional arguments, and handles unknown flag errors"],"goal":"verify github.com/spf13/pflag.NewFlagSet 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.NewFlagSet"]},"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.NewFlagSet"],"verifierAdapter":"golang@1"}

module example.com/pflag-sample

go 1.22.0

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 pflagcli

import (
	"github.com/spf13/pflag"
)

// ServerOptions holds configuration options parsed by FlagSet.
type ServerOptions struct {
	Host    string
	Port    int
	Debug   bool
	Tags    []string
	Timeout int
}

// NewServerFlagSet creates and configures a FlagSet with typed flags.
func NewServerFlagSet(name string, opts *ServerOptions) *pflag.FlagSet {
	fs := pflag.NewFlagSet(name, pflag.ContinueOnError)
	fs.StringVarP(&opts.Host, "host", "h", "127.0.0.1", "Server bind address")
	fs.IntVarP(&opts.Port, "port", "p", 8080, "Server port number")
	fs.BoolVarP(&opts.Debug, "debug", "d", false, "Enable debug mode")
	fs.StringSliceVarP(&opts.Tags, "tags", "t", []string{"api"}, "Service tags")
	fs.IntVar(&opts.Timeout, "timeout", 30, "Request timeout in seconds")
	return fs
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/spf13/pflag.NewFlagSet 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.NewFlagSet"
  ]
}

package main

import (
	"fmt"
	"os"

	pflagcli "example.com/pflag-sample"
	"github.com/spf13/pflag"
)

func main() {
	// Assertion 1: Parse default values when no command-line flags are provided
	var opts1 pflagcli.ServerOptions
	fs1 := pflagcli.NewServerFlagSet("server-default", &opts1)
	if err := fs1.Parse([]string{}); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: default flag parsing failed: %v\n", err)
		os.Exit(1)
	}
	if opts1.Host != "127.0.0.1" || opts1.Port != 8080 || opts1.Debug != false || opts1.Timeout != 30 || len(opts1.Tags) != 1 || opts1.Tags[0] != "api" {
		fmt.Fprintf(os.Stderr, "FAIL: expected defaults (127.0.0.1, 8080, false, 30, [api]), got %+v\n", opts1)
		os.Exit(1)
	}

	// Assertion 2: Parse short flags (-h, -p, -d, -t) and preserve positional arguments
	var opts2 pflagcli.ServerOptions
	fs2 := pflagcli.NewServerFlagSet("server-short", &opts2)
	if err := fs2.Parse([]string{"-h", "0.0.0.0", "-p", "9000", "-d", "-t", "web,metrics", "cmd-arg1", "cmd-arg2"}); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: short flags parsing failed: %v\n", err)
		os.Exit(1)
	}
	if opts2.Host != "0.0.0.0" || opts2.Port != 9000 || opts2.Debug != true || len(opts2.Tags) != 2 || opts2.Tags[0] != "web" || opts2.Tags[1] != "metrics" {
		fmt.Fprintf(os.Stderr, "FAIL: short flags values mismatch: %+v\n", opts2)
		os.Exit(1)
	}
	if fs2.NArg() != 2 || fs2.Args()[0] != "cmd-arg1" || fs2.Args()[1] != "cmd-arg2" {
		fmt.Fprintf(os.Stderr, "FAIL: positional arguments mismatch: %v\n", fs2.Args())
		os.Exit(1)
	}

	// Assertion 3: Parse long flags and verify Changed() status
	var opts3 pflagcli.ServerOptions
	fs3 := pflagcli.NewServerFlagSet("server-long", &opts3)
	if err := fs3.Parse([]string{"--host=192.168.1.1", "--timeout=120"}); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: long flags parsing failed: %v\n", err)
		os.Exit(1)
	}
	if opts3.Host != "192.168.1.1" || opts3.Timeout != 120 {
		fmt.Fprintf(os.Stderr, "FAIL: long flags values mismatch: %+v\n", opts3)
		os.Exit(1)
	}
	if !fs3.Changed("host") || !fs3.Changed("timeout") || fs3.Changed("port") || fs3.Changed("debug") {
		fmt.Fprintf(os.Stderr, "FAIL: Changed() reporting incorrect modification status\n")
		os.Exit(1)
	}

	// Assertion 4: Direct pflag.NewFlagSet usage with typed getters and Lookup
	directFS := pflag.NewFlagSet("direct-test", pflag.ContinueOnError)
	directFS.IntP("workers", "w", 4, "number of worker routines")
	directFS.StringP("target", "T", "local", "target environment")
	if err := directFS.Parse([]string{"-w", "16", "--target=production"}); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: direct flag parsing failed: %v\n", err)
		os.Exit(1)
	}
	wVal, err := directFS.GetInt("workers")
	if err != nil || wVal != 16 {
		fmt.Fprintf(os.Stderr, "FAIL: GetInt('workers') failed: %v, got %d\n", err, wVal)
		os.Exit(1)
	}
	tVal, err := directFS.GetString("target")
	if err != nil || tVal != "production" {
		fmt.Fprintf(os.Stderr, "FAIL: GetString('target') failed: %v, got %s\n", err, tVal)
		os.Exit(1)
	}
	if fl := directFS.Lookup("workers"); fl == nil || fl.Shorthand != "w" {
		fmt.Fprintf(os.Stderr, "FAIL: Lookup('workers') failed or returned invalid shorthand\n")
		os.Exit(1)
	}

	// Assertion 5: Error handling on unknown flag with ContinueOnError
	errFS := pflag.NewFlagSet("err-unknown", pflag.ContinueOnError)
	errFS.String("service", "auth", "service name")
	if err := errFS.Parse([]string{"--nonexistent-flag"}); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error on unknown flag, got nil\n")
		os.Exit(1)
	}

	// Assertion 6: Error handling on type parse error with ContinueOnError
	typeErrFS := pflag.NewFlagSet("err-type", pflag.ContinueOnError)
	typeErrFS.Int("count", 1, "numeric count")
	if err := typeErrFS.Parse([]string{"--count=not-a-number"}); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error on invalid int format, got nil\n")
		os.Exit(1)
	}

	fmt.Println("PASS: pflag.NewFlagSet contract passed")
}