github.com/spf13/pflag v1.0.10: FlagSet.StringArrayVar

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 FlagSet.StringArrayVar 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:
  - FlagSet.StringArrayVar
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:ce3e29e3239e17b27194f4081ecffa5a23a1b8db32e3ed5ca97ce4867f70b302","contract":["FlagSet.StringArrayVar binds a string slice variable to a flag with default values when unparsed","FlagSet.StringArrayVar replaces defaults and appends each flag occurrence without splitting on commas","FlagSet.StringArrayVarP supports shorthand flag syntax and preserves multi-value flag occurrences","FlagSet.StringArrayVar handles empty flag assignments and resets properly across independent FlagSet instances"],"goal":"verify FlagSet.StringArrayVar 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":["FlagSet.StringArrayVar"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"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":["FlagSet.StringArrayVar"],"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 sample

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

// SetupStringArrayFlag registers a string array flag to the FlagSet without shorthand.
func SetupStringArrayFlag(fs *pflag.FlagSet, target *[]string, name string, defaultValue []string, usage string) {
	fs.StringArrayVar(target, name, defaultValue, usage)
}

// SetupStringArrayFlagP registers a string array flag to the FlagSet with shorthand.
func SetupStringArrayFlagP(fs *pflag.FlagSet, target *[]string, name, shorthand string, defaultValue []string, usage string) {
	fs.StringArrayVarP(target, name, shorthand, defaultValue, usage)
}

// ParseFlags parses argument list into the FlagSet.
func ParseFlags(fs *pflag.FlagSet, args []string) error {
	return fs.Parse(args)
}

{
  "schemaVersion": 1,
  "goal": "verify FlagSet.StringArrayVar in pkg:golang/github.com/spf13/pflag@v1.0.10",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/spf13/pflag@v1.0.10"
  ],
  "symbols": [
    "FlagSet.StringArrayVar"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"
	"reflect"

	"github.com/spf13/pflag"
	"sample"
)

func main() {
	// Assertion 1: FlagSet.StringArrayVar binds a variable and retains default values when no args provided
	{
		fs := pflag.NewFlagSet("test-default", pflag.ContinueOnError)
		var items []string
		defaults := []string{"alpha", "beta"}
		sample.SetupStringArrayFlag(fs, &items, "item", defaults, "items list")

		if err := sample.ParseFlags(fs, []string{}); err != nil {
			fmt.Fprintf(os.Stderr, "Parse failed for empty args: %v\n", err)
			os.Exit(1)
		}

		if !reflect.DeepEqual(items, defaults) {
			fmt.Fprintf(os.Stderr, "expected default %v, got %v\n", defaults, items)
			os.Exit(1)
		}
	}

	// Assertion 2: FlagSet.StringArrayVar replaces defaults and preserves comma-separated values literally without splitting
	{
		fs := pflag.NewFlagSet("test-override", pflag.ContinueOnError)
		var headers []string
		sample.SetupStringArrayFlag(fs, &headers, "header", []string{"default:val"}, "HTTP headers")

		args := []string{"--header", "Accept: text/html,application/xhtml+xml", "--header", "User-Agent: test"}
		if err := sample.ParseFlags(fs, args); err != nil {
			fmt.Fprintf(os.Stderr, "Parse failed for repeated flags: %v\n", err)
			os.Exit(1)
		}

		expected := []string{"Accept: text/html,application/xhtml+xml", "User-Agent: test"}
		if !reflect.DeepEqual(headers, expected) {
			fmt.Fprintf(os.Stderr, "expected %v, got %v\n", expected, headers)
			os.Exit(1)
		}
	}

	// Assertion 3: FlagSet.StringArrayVarP supports shorthand flag syntax and preserves multi-value flag occurrences
	{
		fs := pflag.NewFlagSet("test-shorthand", pflag.ContinueOnError)
		var tags []string
		sample.SetupStringArrayFlagP(fs, &tags, "tag", "t", []string{}, "tags")

		args := []string{"-t", "env=prod", "-t", "tier=frontend", "--tag", "region=us-west"}
		if err := sample.ParseFlags(fs, args); err != nil {
			fmt.Fprintf(os.Stderr, "Parse failed for shorthand tags: %v\n", err)
			os.Exit(1)
		}

		expected := []string{"env=prod", "tier=frontend", "region=us-west"}
		if !reflect.DeepEqual(tags, expected) {
			fmt.Fprintf(os.Stderr, "expected %v, got %v\n", expected, tags)
			os.Exit(1)
		}
	}

	// Assertion 4: FlagSet.StringArrayVar handles empty flag assignments and resets properly across independent FlagSet instances
	{
		fs := pflag.NewFlagSet("test-empty", pflag.ContinueOnError)
		var files []string
		sample.SetupStringArrayFlag(fs, &files, "file", []string{"init.txt"}, "files to process")

		args := []string{"--file="}
		if err := sample.ParseFlags(fs, args); err != nil {
			fmt.Fprintf(os.Stderr, "Parse failed for empty flag assignment: %v\n", err)
			os.Exit(1)
		}

		expected := []string{""}
		if !reflect.DeepEqual(files, expected) {
			fmt.Fprintf(os.Stderr, "expected %v, got %v\n", expected, files)
			os.Exit(1)
		}
	}

	fmt.Println("All FlagSet.StringArrayVar contract assertions passed.")
}