github.com/rogpeppe/go-internal v1.3.0: txtar.Archive

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/rogpeppe/go-internal/txtar.Archive in pkg:golang/github.com/rogpeppe/go-internal@v1.3.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/rogpeppe/go-internal@v1.3.0
Demonstrate these symbols/APIs:
  - github.com/rogpeppe/go-internal/txtar.Archive

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:sha256:09b9d00cd0d0c691bdcddd59bec7bcb7c6caaabcd6827881d68a8e85a8939ea4","contract":["txtar.Archive stores comment bytes and a slice of File entries with Name and Data","txtar.Format serializes an Archive with comment header and file marker lines","txtar.Parse reconstructs an Archive from txtar formatted bytes preserving Comment and Files","txtar.Parse returns an empty Archive with no files and empty comment for empty input"],"goal":"verify github.com/rogpeppe/go-internal/txtar.Archive in pkg:golang/github.com/rogpeppe/go-internal@v1.3.0","kind":"HOW","packages":["pkg:golang/github.com/rogpeppe/go-internal@v1.3.0"],"schemaVersion":1,"symbols":["github.com/rogpeppe/go-internal/txtar.Archive"]},"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/rogpeppe/go-internal@v1.3.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/rogpeppe/go-internal@v1.3.0","symbols":["github.com/rogpeppe/go-internal/txtar.Archive"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/rogpeppe/go-internal v1.3.0

github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
github.com/rogpeppe/go-internal v1.3.0 h1:RR9dF3JtopPvtkroDZuVD7qquD0bnHlKSqaQhgwt8yk=
github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=

package main

import (
	"fmt"

	"github.com/rogpeppe/go-internal/txtar"
)

func main() {
	archive := &txtar.Archive{
		Comment: []byte("Archive demonstration\n"),
		Files: []txtar.File{
			{
				Name: "hello.txt",
				Data: []byte("Hello, world!\n"),
			},
			{
				Name: "config.txt",
				Data: []byte("status=active\n"),
			},
		},
	}

	data := txtar.Format(archive)
	fmt.Printf("Formatted archive (%d bytes):\n%s\n", len(data), string(data))

	parsed := txtar.Parse(data)
	fmt.Printf("Parsed comment: %s", string(parsed.Comment))
	for _, f := range parsed.Files {
		fmt.Printf("File: %s -> %s", f.Name, string(f.Data))
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/rogpeppe/go-internal/txtar.Archive in pkg:golang/github.com/rogpeppe/go-internal@v1.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/rogpeppe/go-internal@v1.3.0"
  ],
  "symbols": [
    "github.com/rogpeppe/go-internal/txtar.Archive"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/rogpeppe/go-internal/txtar"
)

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract assertions passed.")
}

func runTests() error {
	// 1. txtar.Archive stores comment bytes and a slice of File entries with Name and Data
	{
		archive := &txtar.Archive{
			Comment: []byte("header comment\n"),
			Files: []txtar.File{
				{Name: "file1.txt", Data: []byte("content 1\n")},
				{Name: "file2.txt", Data: []byte("content 2\n")},
			},
		}
		if string(archive.Comment) != "header comment\n" {
			return fmt.Errorf("assertion 1 failed: expected comment 'header comment\\n', got %q", string(archive.Comment))
		}
		if len(archive.Files) != 2 {
			return fmt.Errorf("assertion 1 failed: expected 2 files, got %d", len(archive.Files))
		}
		if archive.Files[0].Name != "file1.txt" || string(archive.Files[0].Data) != "content 1\n" {
			return fmt.Errorf("assertion 1 failed: file 0 mismatch: %+v", archive.Files[0])
		}
		if archive.Files[1].Name != "file2.txt" || string(archive.Files[1].Data) != "content 2\n" {
			return fmt.Errorf("assertion 1 failed: file 1 mismatch: %+v", archive.Files[1])
		}
	}

	// 2. txtar.Format serializes an Archive with comment header and file marker lines
	{
		archive := &txtar.Archive{
			Comment: []byte("intro note\n"),
			Files: []txtar.File{
				{Name: "msg.txt", Data: []byte("hello\n")},
			},
		}
		formatted := txtar.Format(archive)
		expected := "intro note\n-- msg.txt --\nhello\n"
		if string(formatted) != expected {
			return fmt.Errorf("assertion 2 failed: expected %q, got %q", expected, string(formatted))
		}
	}

	// 3. txtar.Parse reconstructs an Archive from txtar formatted bytes preserving Comment and Files
	{
		input := []byte("comment line\n-- doc.txt --\nsome content\n-- empty.txt --\n")
		parsed := txtar.Parse(input)
		if string(parsed.Comment) != "comment line\n" {
			return fmt.Errorf("assertion 3 failed: expected comment 'comment line\\n', got %q", string(parsed.Comment))
		}
		if len(parsed.Files) != 2 {
			return fmt.Errorf("assertion 3 failed: expected 2 files, got %d", len(parsed.Files))
		}
		if parsed.Files[0].Name != "doc.txt" || string(parsed.Files[0].Data) != "some content\n" {
			return fmt.Errorf("assertion 3 failed: file 0 mismatch: %+v", parsed.Files[0])
		}
		if parsed.Files[1].Name != "empty.txt" || len(parsed.Files[1].Data) != 0 {
			return fmt.Errorf("assertion 3 failed: file 1 mismatch: %+v", parsed.Files[1])
		}
	}

	// 4. txtar.Parse returns an empty Archive with no files and empty comment for empty input
	{
		parsed := txtar.Parse([]byte(""))
		if len(parsed.Comment) != 0 {
			return fmt.Errorf("assertion 4 failed: expected empty comment, got %q", string(parsed.Comment))
		}
		if len(parsed.Files) != 0 {
			return fmt.Errorf("assertion 4 failed: expected 0 files, got %d", len(parsed.Files))
		}
	}

	return nil
}