golang.org/x/net v0.0.0-20190311183353-d8887717615a: idna.ToUnicode

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/idna.ToUnicode in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a
Demonstrate these symbols/APIs:
  - golang.org/x/net/idna.ToUnicode

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:cc4e64329814342373b3607156af5225d8309f30a9def9cd9f0a7c7c8f939831","contract":["idna.ToUnicode converts ASCII Punycode domain names back to their Unicode representation"],"goal":"verify golang.org/x/net/idna.ToUnicode in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a"],"schemaVersion":1,"symbols":["golang.org/x/net/idna.ToUnicode"]},"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@v0.0.0-20190311183353-d8887717615a"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a","symbols":["golang.org/x/net/idna.ToUnicode"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22

require golang.org/x/net v0.0.0-20190311183353-d8887717615a

require golang.org/x/text v0.3.0 // indirect

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20190311183353-d8887717615a h1:oWX7TPOiFAMXLq8o0ikBYfCJVlRHBcsciT5bXOrH628=
golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

package main

import (
	"fmt"
	"log"

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

func main() {
	asciiDomain := "xn--bcher-kva.example.com"
	unicodeDomain, err := idna.ToUnicode(asciiDomain)
	if err != nil {
		log.Fatalf("idna.ToUnicode failed: %v", err)
	}
	fmt.Printf("ASCII domain %s converted to Unicode: %s\n", asciiDomain, unicodeDomain)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/idna.ToUnicode in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a"
  ],
  "symbols": [
    "golang.org/x/net/idna.ToUnicode"
  ]
}

package main

import (
	"fmt"
	"os"

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

func main() {
	// Assertion 1: idna.ToUnicode converts ASCII Punycode domain names back to their Unicode representation
	{
		testCases := []struct {
			input string
			want  string
		}{
			{"example.com", "example.com"},
			{"xn--bcher-kva.example.com", "bücher.example.com"},
			{"xn--mnchen-3ya.de", "münchen.de"},
		}

		for _, tc := range testCases {
			got, err := idna.ToUnicode(tc.input)
			if err != nil {
				fmt.Fprintf(os.Stderr, "assertion failed: ToUnicode(%q) returned error: %v\n", tc.input, err)
				os.Exit(1)
			}
			if got != tc.want {
				fmt.Fprintf(os.Stderr, "assertion failed: ToUnicode(%q) = %q, want %q\n", tc.input, got, tc.want)
				os.Exit(1)
			}
		}
	}

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