golang.org/x/text v0.27.0

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/golang.org/x/text@v0.27.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/text@v0.27.0

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:acfdbc7bc0f054306524cbddaf1dea907d68d51ecbdb38b56d3fc4639479b270","contract":["language.Make creates valid Tags and language.NewMatcher matches regional variants like BritishEnglish to server supported English (index 0)","cases.Title with language.English properly title-cases English words","cases.Upper with language.Turkish converts lowercase i to dotted capital I","norm.NFD decomposes precomposed characters and norm.NFC recomposes them","width.Narrow converts fullwidth ASCII and space characters to halfwidth counterparts"],"goal":"verify pkg:golang/golang.org/x/text@v0.27.0","kind":"HOW","packages":["pkg:golang/golang.org/x/text@v0.27.0"],"schemaVersion":1},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/text@v0.27.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/text@v0.27.0","verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/text v0.27.0

golang.org/x/text v0.27.0 h1:4fGWRpyh641NLlecmyl4LOe6yDdfaYNrGb2zdfo4JV4=
golang.org/x/text v0.27.0/go.mod h1:1D28KMCvyooCX9hBiosv5Tz/+YLxj0j7XhWjpSUF7CU=

package main

import (
	"fmt"

	"golang.org/x/text/cases"
	"golang.org/x/text/language"
	"golang.org/x/text/unicode/norm"
	"golang.org/x/text/width"
)

func main() {
	// 1. Language tag creation and matching
	tag := language.Make("en-US")
	fmt.Printf("Language tag: %s (Base: %s)\n", tag.String(), tag.Parent().String())

	serverLangs := []language.Tag{
		language.English,
		language.German,
		language.French,
	}
	matcher := language.NewMatcher(serverLangs)
	matched, index, conf := matcher.Match(language.BritishEnglish)
	fmt.Printf("Matched %s to %s (selected serverLang %s at index %d, conf %v)\n",
		language.BritishEnglish, matched, serverLangs[index], index, conf)

	// 2. Language-sensitive casing
	titleCaser := cases.Title(language.English)
	fmt.Println("Title case:", titleCaser.String("the quick brown fox"))

	turkishUpper := cases.Upper(language.Turkish)
	fmt.Println("Turkish upper:", turkishUpper.String("istanbul"))

	// 3. Unicode normalization
	composed := "é"
	decomposed := norm.NFD.String(composed)
	fmt.Printf("NFD length: %d, NFC length: %d\n", len(decomposed), len(norm.NFC.String(decomposed)))

	// 4. Width transformation (fullwidth to halfwidth)
	fullwidth := "ＡＢＣ　１２３"
	halfwidth := width.Narrow.String(fullwidth)
	fmt.Println("Narrow:", halfwidth)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/golang.org/x/text@v0.27.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/text@v0.27.0"
  ]
}

package main

import (
	"fmt"
	"os"

	"golang.org/x/text/cases"
	"golang.org/x/text/language"
	"golang.org/x/text/unicode/norm"
	"golang.org/x/text/width"
)

func main() {
	// Assertion 1: language.Make creates valid Tags and language.NewMatcher matches regional variants like BritishEnglish to server supported English (index 0)
	enUS := language.Make("en-US")
	if enUS.String() != "en-US" {
		fmt.Fprintf(os.Stderr, "FAIL: expected 'en-US', got %q\n", enUS.String())
		os.Exit(1)
	}

	serverLangs := []language.Tag{
		language.English,
		language.German,
		language.French,
	}
	matcher := language.NewMatcher(serverLangs)
	_, index, conf := matcher.Match(language.BritishEnglish)
	if index != 0 || serverLangs[index] != language.English || conf < language.High {
		fmt.Fprintf(os.Stderr, "FAIL: expected match to English at index 0, got index %d with conf %v\n", index, conf)
		os.Exit(1)
	}

	// Assertion 2: cases.Title with language.English properly title-cases English words
	titleCaser := cases.Title(language.English)
	if res := titleCaser.String("hello world"); res != "Hello World" {
		fmt.Fprintf(os.Stderr, "FAIL: expected 'Hello World', got %q\n", res)
		os.Exit(1)
	}

	// Assertion 3: cases.Upper with language.Turkish converts lowercase i to dotted capital I
	turkishUpper := cases.Upper(language.Turkish)
	if res := turkishUpper.String("istanbul"); res != "İSTANBUL" {
		fmt.Fprintf(os.Stderr, "FAIL: expected 'İSTANBUL', got %q\n", res)
		os.Exit(1)
	}

	// Assertion 4: norm.NFD decomposes precomposed characters and norm.NFC recomposes them
	composed := "\u00e9" // é (single rune)
	decomposed := norm.NFD.String(composed)
	if decomposed != "e\u0301" || len(decomposed) <= len(composed) {
		fmt.Fprintf(os.Stderr, "FAIL: norm.NFD failed: got %q (len %d)\n", decomposed, len(decomposed))
		os.Exit(1)
	}
	recomposed := norm.NFC.String(decomposed)
	if recomposed != composed {
		fmt.Fprintf(os.Stderr, "FAIL: norm.NFC failed: expected %q, got %q\n", composed, recomposed)
		os.Exit(1)
	}

	// Assertion 5: width.Narrow converts fullwidth ASCII and space characters to halfwidth counterparts
	fullwidth := "ＡＢＣ　１２３"
	narrow := width.Narrow.String(fullwidth)
	if narrow != "ABC 123" {
		fmt.Fprintf(os.Stderr, "FAIL: width.Narrow expected 'ABC 123', got %q\n", narrow)
		os.Exit(1)
	}

	fmt.Println("PASS: pkg:golang/golang.org/x/text@v0.27.0 contract verified")
}