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

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 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

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:fc82bc3894de40e4c4ff1f2f74a95a7b61208921991a6e022cbd996341416b6c","contract":["txtar.Parse parses comments and file sections with names and contents","txtar.Format serializes an Archive back into txtar byte representation","txtar.Parse handles multiple files and preserves trailing newlines","txtar.Parse handles empty archive without error and returns empty file list","semver.Compare correctly orders semantic version strings with v prefix","semver.IsValid returns true for valid semver strings and false for invalid strings"],"goal":"verify 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},"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","verifierAdapter":"golang@1"}

module example.com/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 (
	"bytes"
	"fmt"

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

func main() {
	archiveData := []byte(`archive comment
-- hello.txt --
Hello, world!
-- data/info.json --
{"status": "ok"}
`)

	archive := txtar.Parse(archiveData)
	fmt.Printf("Comment: %s\n", bytes.TrimSpace(archive.Comment))
	fmt.Printf("Files count: %d\n", len(archive.Files))
	for _, f := range archive.Files {
		fmt.Printf("File: %s, Size: %d\n", f.Name, len(f.Data))
	}

	formatted := txtar.Format(archive)
	fmt.Printf("Formatted length: %d bytes\n", len(formatted))

	v1 := "v1.2.0"
	v2 := "v1.3.0"
	fmt.Printf("Compare %s and %s: %d\n", v1, v2, semver.Compare(v1, v2))
	fmt.Printf("Is %s valid semver: %t\n", v1, semver.IsValid(v1))
	fmt.Printf("Major version of %s: %s\n", v1, semver.Major(v1))
}

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

package main

import (
	"bytes"
	"fmt"
	"os"

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

func main() {
	// 1. txtar.Parse parses comments and file sections with names and contents
	{
		raw := []byte("comment line\n-- file1.txt --\nfile content\n")
		a := txtar.Parse(raw)
		if string(bytes.TrimSpace(a.Comment)) != "comment line" {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: comment mismatch, got %q\n", string(a.Comment))
			os.Exit(1)
		}
		if len(a.Files) != 1 {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected 1 file, got %d\n", len(a.Files))
			os.Exit(1)
		}
		if a.Files[0].Name != "file1.txt" || string(bytes.TrimSpace(a.Files[0].Data)) != "file content" {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: file content mismatch\n")
			os.Exit(1)
		}
	}

	// 2. txtar.Format serializes an Archive back into txtar byte representation
	{
		a := &txtar.Archive{
			Comment: []byte("test comment\n"),
			Files: []txtar.File{
				{
					Name: "a.txt",
					Data: []byte("content A\n"),
				},
			},
		}
		out := txtar.Format(a)
		reparsed := txtar.Parse(out)
		if string(reparsed.Comment) != string(a.Comment) {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: comment roundtrip mismatch\n")
			os.Exit(1)
		}
		if len(reparsed.Files) != 1 || reparsed.Files[0].Name != "a.txt" || !bytes.Equal(reparsed.Files[0].Data, a.Files[0].Data) {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: file roundtrip mismatch\n")
			os.Exit(1)
		}
	}

	// 3. txtar.Parse handles multiple files and preserves trailing newlines
	{
		raw := []byte("-- f1.txt --\nline 1\n-- f2.txt --\nline 2\nline 3\n")
		a := txtar.Parse(raw)
		if len(a.Files) != 2 {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected 2 files, got %d\n", len(a.Files))
			os.Exit(1)
		}
		if a.Files[0].Name != "f1.txt" || string(a.Files[0].Data) != "line 1\n" {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: f1 data mismatch\n")
			os.Exit(1)
		}
		if a.Files[1].Name != "f2.txt" || string(a.Files[1].Data) != "line 2\nline 3\n" {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: f2 data mismatch\n")
			os.Exit(1)
		}
	}

	// 4. txtar.Parse handles empty archive without error and returns empty file list
	{
		a := txtar.Parse([]byte(""))
		if len(a.Comment) != 0 || len(a.Files) != 0 {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: empty input should yield empty archive\n")
			os.Exit(1)
		}
	}

	// 5. semver.Compare correctly orders semantic version strings with v prefix
	{
		if semver.Compare("v1.2.0", "v1.3.0") >= 0 {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: v1.2.0 should be less than v1.3.0\n")
			os.Exit(1)
		}
		if semver.Compare("v2.0.0", "v1.9.9") <= 0 {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: v2.0.0 should be greater than v1.9.9\n")
			os.Exit(1)
		}
		if semver.Compare("v1.0.0", "v1.0.0") != 0 {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: identical versions should compare equal\n")
			os.Exit(1)
		}
	}

	// 6. semver.IsValid returns true for valid semver strings and false for invalid strings
	{
		if !semver.IsValid("v1.3.0") {
			fmt.Fprintf(os.Stderr, "Assertion 6 failed: v1.3.0 should be valid\n")
			os.Exit(1)
		}
		if semver.IsValid("1.3.0") { // missing 'v' prefix
			fmt.Fprintf(os.Stderr, "Assertion 6 failed: 1.3.0 without v should be invalid\n")
			os.Exit(1)
		}
		if semver.IsValid("not-a-version") {
			fmt.Fprintf(os.Stderr, "Assertion 6 failed: invalid string accepted as semver\n")
			os.Exit(1)
		}
	}

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