golang.org/x/net v0.38.0: publicsuffix.EffectiveTLDPlusOne, publicsuffix.PublicSuffix

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 golang.org/x/net/publicsuffix.EffectiveTLDPlusOne and PublicSuffix in pkg:golang/golang.org/x/net@v0.38.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.38.0
Demonstrate these symbols/APIs:
  - golang.org/x/net/publicsuffix.EffectiveTLDPlusOne
  - golang.org/x/net/publicsuffix.PublicSuffix
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:sha256:9ace36a06a4bc5814b955d962ea010f33aea5476bf2426266ef342661d922001","contract":["publicsuffix.PublicSuffix returns the public suffix and whether it is managed by ICANN for domains","publicsuffix.EffectiveTLDPlusOne extracts the effective top-level domain plus one label, or returns an error for invalid domains"],"goal":"verify golang.org/x/net/publicsuffix.EffectiveTLDPlusOne and PublicSuffix in pkg:golang/golang.org/x/net@v0.38.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.38.0"],"schemaVersion":1,"symbols":["golang.org/x/net/publicsuffix.EffectiveTLDPlusOne","golang.org/x/net/publicsuffix.PublicSuffix"]},"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/golang.org/x/net@v0.38.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.38.0","symbols":["golang.org/x/net/publicsuffix.EffectiveTLDPlusOne","golang.org/x/net/publicsuffix.PublicSuffix"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.23.0

require golang.org/x/net v0.38.0

golang.org/x/net v0.38.0 h1:vRMAPTMaeGqVhG5QyLJHqNDwecKTomGeqbnfZyKlBI8=
golang.org/x/net v0.38.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=

package main

import (
	"fmt"
	"log"

	"golang.org/x/net/publicsuffix"
)

func main() {
	domain := "sub.example.co.uk"

	ps, icann := publicsuffix.PublicSuffix(domain)
	fmt.Printf("Domain: %s -> Public Suffix: %s (ICANN: %v)\n", domain, ps, icann)

	etld1, err := publicsuffix.EffectiveTLDPlusOne(domain)
	if err != nil {
		log.Fatalf("failed to get eTLD+1: %v", err)
	}
	fmt.Printf("Domain: %s -> eTLD+1: %s\n", domain, etld1)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/publicsuffix.EffectiveTLDPlusOne and PublicSuffix in pkg:golang/golang.org/x/net@v0.38.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.38.0"
  ],
  "symbols": [
    "golang.org/x/net/publicsuffix.EffectiveTLDPlusOne",
    "golang.org/x/net/publicsuffix.PublicSuffix"
  ],
  "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"

	"golang.org/x/net/publicsuffix"
)

func main() {
	// Assertion 1: publicsuffix.PublicSuffix returns the public suffix and whether it is managed by ICANN for domains
	{
		ps, icann := publicsuffix.PublicSuffix("www.example.com")
		if ps != "com" || !icann {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected ('com', true), got (%q, %v)\n", ps, icann)
			os.Exit(1)
		}

		psUk, icannUk := publicsuffix.PublicSuffix("foo.co.uk")
		if psUk != "co.uk" || !icannUk {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected ('co.uk', true), got (%q, %v)\n", psUk, icannUk)
			os.Exit(1)
		}

		psCustom, icannCustom := publicsuffix.PublicSuffix("my-app.github.io")
		if psCustom != "github.io" || icannCustom {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected ('github.io', false), got (%q, %v)\n", psCustom, icannCustom)
			os.Exit(1)
		}
	}

	// Assertion 2: publicsuffix.EffectiveTLDPlusOne extracts the effective top-level domain plus one label, or returns an error for invalid domains
	{
		etld1, err := publicsuffix.EffectiveTLDPlusOne("sub.example.co.uk")
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected error for valid domain: %v\n", err)
			os.Exit(1)
		}
		if etld1 != "example.co.uk" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 'example.co.uk', got %q\n", etld1)
			os.Exit(1)
		}

		etld1DotCom, err := publicsuffix.EffectiveTLDPlusOne("a.b.c.example.com")
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if etld1DotCom != "example.com" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 'example.com', got %q\n", etld1DotCom)
			os.Exit(1)
		}

		_, errInvalid := publicsuffix.EffectiveTLDPlusOne("com")
		if errInvalid == nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected error for top-level domain 'com', got nil\n")
			os.Exit(1)
		}

		_, errEmpty := publicsuffix.EffectiveTLDPlusOne("")
		if errEmpty == nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected error for empty domain, got nil\n")
			os.Exit(1)
		}
	}

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