golang.org/x/text v0.3.6: language.Parse

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/language.Parse in pkg:golang/golang.org/x/text@v0.3.6
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/text@v0.3.6
Demonstrate these symbols/APIs:
  - golang.org/x/text/language.Parse
Required runtime conditions:
  - ecosystem: golang
  - language: go
  - packageManager: go@1.26.6
  - runtime: go@1.26.6

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:b8467c800e347ce79015a1990e65b5dd48051326aa989684c95facef884a1f23","contract":["language.Parse parses valid BCP 47 language tags into a Tag","language.Parse canonicalizes tag casing to standard BCP 47 format","language.Parse extracts correct base language script and region from compound tags","language.Parse preserves BCP 47 extension subtags","language.Parse returns an error for invalid or ill-formed language tags","language.Parse returns an error for empty string input"],"goal":"verify golang.org/x/text/language.Parse in pkg:golang/golang.org/x/text@v0.3.6","kind":"HOW","packages":["pkg:golang/golang.org/x/text@v0.3.6"],"schemaVersion":1,"symbols":["golang.org/x/text/language.Parse"]},"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@v0.3.6"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/text@v0.3.6","symbols":["golang.org/x/text/language.Parse"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/text v0.3.6

golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

package main

import (
	"fmt"
	"log"

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

func main() {
	// Parse a standard BCP 47 language tag
	tag, err := language.Parse("en-US")
	if err != nil {
		log.Fatalf("failed to parse en-US: %v", err)
	}
	fmt.Printf("Parsed tag: %s\n", tag)

	base, _ := tag.Base()
	region, _ := tag.Region()
	fmt.Printf("Base: %s, Region: %s\n", base, region)

	// Parse with lowercase region to show canonicalization
	canonicalTag, err := language.Parse("fr-ca")
	if err != nil {
		log.Fatalf("failed to parse fr-ca: %v", err)
	}
	fmt.Printf("Canonicalized tag: %s\n", canonicalTag)

	// Attempt to parse an invalid tag
	_, err = language.Parse("invalid---tag")
	if err != nil {
		fmt.Printf("Correctly rejected invalid tag: %v\n", err)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/text/language.Parse in pkg:golang/golang.org/x/text@v0.3.6",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/text@v0.3.6"
  ],
  "symbols": [
    "golang.org/x/text/language.Parse"
  ],
  "runtimeConditions": {
    "ecosystem": "golang",
    "language": "go",
    "packageManager": "go@1.26.6",
    "runtime": "go@1.26.6"
  }
}

package main

import (
	"fmt"
	"os"

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

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. language.Parse parses valid BCP 47 language tags into a Tag
	{
		tag, err := language.Parse("en")
		if err != nil {
			return fmt.Errorf("assertion 1 failed: language.Parse(\"en\") returned error: %w", err)
		}
		if tag.String() != "en" {
			return fmt.Errorf("assertion 1 failed: expected \"en\", got %q", tag.String())
		}
	}

	// 2. language.Parse canonicalizes tag casing to standard BCP 47 format
	{
		tag, err := language.Parse("en-us")
		if err != nil {
			return fmt.Errorf("assertion 2 failed: language.Parse(\"en-us\") returned error: %w", err)
		}
		if tag.String() != "en-US" {
			return fmt.Errorf("assertion 2 failed: expected \"en-US\", got %q", tag.String())
		}

		tag2, err2 := language.Parse("ZH-hAnT-tw")
		if err2 != nil {
			return fmt.Errorf("assertion 2 failed: language.Parse(\"ZH-hAnT-tw\") returned error: %w", err2)
		}
		if tag2.String() != "zh-Hant-TW" {
			return fmt.Errorf("assertion 2 failed: expected \"zh-Hant-TW\", got %q", tag2.String())
		}
	}

	// 3. language.Parse extracts correct base language script and region from compound tags
	{
		tag, err := language.Parse("zh-Hant-TW")
		if err != nil {
			return fmt.Errorf("assertion 3 failed: language.Parse(\"zh-Hant-TW\") returned error: %w", err)
		}
		base, _ := tag.Base()
		if base.String() != "zh" {
			return fmt.Errorf("assertion 3 failed: expected base \"zh\", got %q", base.String())
		}
		script, _ := tag.Script()
		if script.String() != "Hant" {
			return fmt.Errorf("assertion 3 failed: expected script \"Hant\", got %q", script.String())
		}
		region, _ := tag.Region()
		if region.String() != "TW" {
			return fmt.Errorf("assertion 3 failed: expected region \"TW\", got %q", region.String())
		}
	}

	// 4. language.Parse preserves BCP 47 extension subtags
	{
		tag, err := language.Parse("de-CH-u-co-phonebk")
		if err != nil {
			return fmt.Errorf("assertion 4 failed: language.Parse(\"de-CH-u-co-phonebk\") returned error: %w", err)
		}
		if tag.String() != "de-CH-u-co-phonebk" {
			return fmt.Errorf("assertion 4 failed: expected \"de-CH-u-co-phonebk\", got %q", tag.String())
		}
	}

	// 5. language.Parse returns an error for invalid or ill-formed language tags
	{
		_, err := language.Parse("invalid---tag")
		if err == nil {
			return fmt.Errorf("assertion 5 failed: expected error for \"invalid---tag\", got nil")
		}
		_, err = language.Parse("123456789")
		if err == nil {
			return fmt.Errorf("assertion 5 failed: expected error for \"123456789\", got nil")
		}
	}

	// 6. language.Parse returns an error for empty string input
	{
		_, err := language.Parse("")
		if err == nil {
			return fmt.Errorf("assertion 6 failed: expected error for empty string, got nil")
		}
	}

	return nil
}