golang.org/x/text v0.16.0: cases.Upper

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/text/cases.Upper in pkg:golang/golang.org/x/text@v0.16.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/text@v0.16.0
Demonstrate these symbols/APIs:
  - golang.org/x/text/cases.Upper

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:sha256:1f9e7839f6b1696210f4c6cdc8ca3b0d9d2199c86e5abc45e1f54d5fd7cf8270","contract":["cases.Upper with language.Und transforms ASCII lowercase strings to uppercase","cases.Upper Bytes method transforms byte slices matching String output","cases.Upper with language.Turkish converts lowercase 'i' to dotted uppercase 'İ' and 'ı' to dotless uppercase 'I'","cases.Upper with language.German transforms lowercase sharp 'ß' to uppercase 'SS'","cases.Upper with language.Greek strips accents and transforms lowercase Greek letters to uppercase","cases.Upper implements transform.Transformer interface and transforms byte buffers"],"goal":"verify golang.org/x/text/cases.Upper in pkg:golang/golang.org/x/text@v0.16.0","kind":"HOW","packages":["pkg:golang/golang.org/x/text@v0.16.0"],"schemaVersion":1,"symbols":["golang.org/x/text/cases.Upper"]},"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/text@v0.16.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/text@v0.16.0","symbols":["golang.org/x/text/cases.Upper"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/text v0.16.0

golang.org/x/text v0.16.0 h1:a94ExnEXNtEwYLGJSIUxnWoxoRz/ZcCsV63ROupILh4=
golang.org/x/text v0.16.0/go.mod h1:GhwF1Be+LQoKShO3cGOHzqOgRrGaYc9AvblQOmPVHnI=

package main

import (
	"fmt"

	"golang.org/x/text/cases"
	"golang.org/x/text/language"
)

func main() {
	undUpper := cases.Upper(language.Und)
	fmt.Printf("Und: %s\n", undUpper.String("hello world"))

	trUpper := cases.Upper(language.Turkish)
	fmt.Printf("Turkish: %s\n", trUpper.String("istanbul"))

	deUpper := cases.Upper(language.German)
	fmt.Printf("German: %s\n", deUpper.String("groß"))
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/text/cases.Upper in pkg:golang/golang.org/x/text@v0.16.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/text@v0.16.0"
  ],
  "symbols": [
    "golang.org/x/text/cases.Upper"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"

	"golang.org/x/text/cases"
	"golang.org/x/text/language"
	"golang.org/x/text/transform"
)

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. cases.Upper with language.Und transforms ASCII lowercase strings to uppercase
	uUnd := cases.Upper(language.Und)
	if got := uUnd.String("hello world"); got != "HELLO WORLD" {
		return fmt.Errorf("expected 'HELLO WORLD', got %q", got)
	}

	// 2. cases.Upper Bytes method transforms byte slices matching String output
	b := []byte("golang text")
	gotB := uUnd.Bytes(b)
	if !bytes.Equal(gotB, []byte("GOLANG TEXT")) {
		return fmt.Errorf("expected 'GOLANG TEXT', got %q", string(gotB))
	}

	// 3. cases.Upper with language.Turkish converts lowercase 'i' to dotted uppercase 'İ' and 'ı' to dotless uppercase 'I'
	uTr := cases.Upper(language.Turkish)
	if got := uTr.String("istanbul"); got != "\u0130STANBUL" {
		return fmt.Errorf("expected '\\u0130STANBUL', got %q", got)
	}
	if got := uTr.String("\u0131"); got != "I" {
		return fmt.Errorf("expected 'I', got %q", got)
	}

	// 4. cases.Upper with language.German transforms lowercase sharp 'ß' to uppercase 'SS'
	uDe := cases.Upper(language.German)
	if got := uDe.String("groß"); got != "GROSS" {
		return fmt.Errorf("expected 'GROSS', got %q", got)
	}

	// 5. cases.Upper with language.Greek strips accents and transforms lowercase Greek letters to uppercase
	uEl := cases.Upper(language.Greek)
	if got := uEl.String("Ὀδυσσεύς"); got != "ΟΔΥΣΣΕΥΣ" {
		return fmt.Errorf("expected 'ΟΔΥΣΣΕΥΣ', got %q", got)
	}

	// 6. cases.Upper implements transform.Transformer interface and transforms byte buffers
	var tr transform.Transformer = uUnd
	dst := make([]byte, 16)
	nDst, nSrc, err := tr.Transform(dst, []byte("cases"), true)
	if err != nil {
		return fmt.Errorf("transform returned unexpected error: %w", err)
	}
	if nDst != 5 || nSrc != 5 || string(dst[:nDst]) != "CASES" {
		return fmt.Errorf("expected 5 bytes transformed to 'CASES', got nDst=%d, nSrc=%d, dst=%q", nDst, nSrc, string(dst[:nDst]))
	}

	return nil
}