golang.org/x/text v0.31.0: ianaindex.IANA

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/encoding/ianaindex.IANA in pkg:golang/golang.org/x/text@v0.31.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/text@v0.31.0
Demonstrate these symbols/APIs:
  - golang.org/x/text/encoding/ianaindex.IANA

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:a456774db208ed1439acba4baff93634b3bc8654175e6f2ca6109339551d996c","contract":["ianaindex.IANA.Encoding resolves standard charset names and aliases case-insensitively with whitespace trimmed","ianaindex.IANA.Name reports canonical IANA identifiers for standard encodings","ianaindex.IANA.Encoding returns an error for invalid or unregistered charset names","ianaindex.IANA.Name returns an error for encodings not associated with a known IANA identifier"],"goal":"verify golang.org/x/text/encoding/ianaindex.IANA in pkg:golang/golang.org/x/text@v0.31.0","kind":"HOW","packages":["pkg:golang/golang.org/x/text@v0.31.0"],"schemaVersion":1,"symbols":["golang.org/x/text/encoding/ianaindex.IANA"]},"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@v0.31.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/text@v0.31.0","symbols":["golang.org/x/text/encoding/ianaindex.IANA"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/text v0.31.0

golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=

package main

import (
	"fmt"
	"os"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/charmap"
	"golang.org/x/text/encoding/ianaindex"
	"golang.org/x/text/encoding/unicode"
)

// ResolveIANAEncoding looks up an encoding by IANA name or alias and reports its canonical IANA name.
func ResolveIANAEncoding(name string) (encoding.Encoding, string, error) {
	enc, err := ianaindex.IANA.Encoding(name)
	if err != nil {
		return nil, "", err
	}
	if enc == nil {
		return nil, "", fmt.Errorf("encoding %q registered but unsupported", name)
	}
	canonical, err := ianaindex.IANA.Name(enc)
	if err != nil {
		return enc, "", err
	}
	return enc, canonical, nil
}

func main() {
	charsets := []string{"utf-8", "  l5  ", "cp437", "shift_jis"}
	for _, cs := range charsets {
		enc, canonical, err := ResolveIANAEncoding(cs)
		if err != nil {
			fmt.Fprintf(os.Stderr, "failed to resolve %q: %v\n", cs, err)
			os.Exit(1)
		}
		fmt.Printf("Input: %q -> Canonical IANA: %q, Resolved: %v\n", cs, canonical, enc != nil)
	}

	// Demonstration of IANA.Name on explicit encodings
	utf16be := unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM)
	canonical16, err := ianaindex.IANA.Name(utf16be)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to get name for UTF-16BE: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("UTF16BE canonical name: %s\n", canonical16)

	isoName, err := ianaindex.IANA.Name(charmap.ISO8859_7)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to get name for ISO8859-7: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("ISO8859-7 canonical name: %s\n", isoName)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/text/encoding/ianaindex.IANA in pkg:golang/golang.org/x/text@v0.31.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/text@v0.31.0"
  ],
  "symbols": [
    "golang.org/x/text/encoding/ianaindex.IANA"
  ]
}

package main

import (
	"fmt"
	"os"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/charmap"
	"golang.org/x/text/encoding/ianaindex"
	"golang.org/x/text/encoding/japanese"
	"golang.org/x/text/encoding/unicode"
)

func main() {
	// Assertion 1: ianaindex.IANA.Encoding resolves standard charset names and aliases case-insensitively with whitespace trimmed
	testCasesEnc := []struct {
		input     string
		wantCanonical string
	}{
		{"utf-8", "UTF-8"},
		{"  utf-8  ", "UTF-8"},
		{"  l5  ", "ISO_8859-9:1989"},
		{"LATIN5 ", "ISO_8859-9:1989"},
		{"cp437", "IBM437"},
		{"shift_jis", "Shift_JIS"},
	}

	for _, tc := range testCasesEnc {
		enc, err := ianaindex.IANA.Encoding(tc.input)
		if err != nil || enc == nil {
			fmt.Fprintf(os.Stderr, "FAIL: ianaindex.IANA.Encoding(%q) unexpected error=%v, enc=%v\n", tc.input, err, enc)
			os.Exit(1)
		}
		canonical, err := ianaindex.IANA.Name(enc)
		if err != nil || canonical != tc.wantCanonical {
			fmt.Fprintf(os.Stderr, "FAIL: ianaindex.IANA.Name after Encoding(%q) got %q, err=%v; want %q\n", tc.input, canonical, err, tc.wantCanonical)
			os.Exit(1)
		}
	}

	// Assertion 2: ianaindex.IANA.Name reports canonical IANA identifiers for standard encodings
	testCasesName := []struct {
		enc           encoding.Encoding
		wantCanonical string
	}{
		{unicode.UTF8, "UTF-8"},
		{unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM), "UTF-16BE"},
		{charmap.ISO8859_7, "ISO_8859-7:1987"},
		{charmap.CodePage437, "IBM437"},
		{japanese.ShiftJIS, "Shift_JIS"},
	}

	for _, tc := range testCasesName {
		canonical, err := ianaindex.IANA.Name(tc.enc)
		if err != nil || canonical != tc.wantCanonical {
			fmt.Fprintf(os.Stderr, "FAIL: ianaindex.IANA.Name(%v) got %q, err=%v; want %q\n", tc.enc, canonical, err, tc.wantCanonical)
			os.Exit(1)
		}
	}

	// Assertion 3: ianaindex.IANA.Encoding returns an error for invalid or unregistered charset names
	invalidNames := []string{"latin-5", "latin 5", "invalid_charset_xyz", "not-a-real-encoding"}
	for _, name := range invalidNames {
		enc, err := ianaindex.IANA.Encoding(name)
		if err == nil {
			fmt.Fprintf(os.Stderr, "FAIL: ianaindex.IANA.Encoding(%q) expected error, got nil (enc=%v)\n", name, enc)
			os.Exit(1)
		}
	}

	// Assertion 4: ianaindex.IANA.Name returns an error for encodings not associated with a known IANA identifier
	if _, err := ianaindex.IANA.Name(encoding.Nop); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: ianaindex.IANA.Name(encoding.Nop) expected error, got nil\n")
		os.Exit(1)
	}

	fmt.Println("PASS: golang.org/x/text/encoding/ianaindex.IANA contract verified")
}