github.com/google/uuid v1.6.0: generate and parse UUID v4

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: generate and parse UUID v4
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/uuid@v1.6.0
Demonstrate these symbols/APIs:
  - uuid.NewString
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@11.8.0
  - runtime: node@24.13.1

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:b36d6192d0010fd23eb7292edc87454138ce6fa6aabe25df5cc7bcf54aac003b","contract":["uuid.NewString generates a valid RFC 4122 v4 UUID string","uuid.Parse parses a valid canonical UUID string into a UUID value","uuid.Parse returns an error for invalid UUID strings","uuid.New returns a UUID value with version 4 and variant RFC4122","uuid.MustParse parses valid UUID string and panics on invalid input"],"goal":"generate and parse UUID v4","kind":"HOW","packages":["pkg:golang/github.com/google/uuid@v1.6.0"],"schemaVersion":1,"symbols":["uuid.NewString"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","ecosystem":"golang","os":"windows","osVersionBucket":"11","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/google/uuid@v1.6.0"],"schemaVersion":1,"symbols":["uuid.NewString"],"verifierAdapter":"golang@1"}

module sample

go 1.26.5

require github.com/google/uuid v1.6.0 // indirect

github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=

package main

import (
	"fmt"

	"github.com/google/uuid"
)

func main() {
	// Generate a random RFC 4122 v4 UUID as string
	idStr := uuid.NewString()
	fmt.Printf("Generated UUID string: %s\n", idStr)

	// Parse the UUID string
	parsed, err := uuid.Parse(idStr)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Parsed UUID: %s (Version: %d, Variant: %s)\n",
		parsed.String(), parsed.Version(), parsed.Variant().String())

	// Generate binary UUID
	id := uuid.New()
	fmt.Printf("Generated binary UUID: %s\n", id.String())
}

{
  "schemaVersion": 1,
  "goal": "generate and parse UUID v4",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/google/uuid@v1.6.0"
  ],
  "symbols": [
    "uuid.NewString"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@11.8.0",
    "runtime": "node@24.13.1"
  }
}

package main

import (
	"fmt"
	"os"

	"github.com/google/uuid"
)

func main() {
	// Assertion 1: uuid.NewString generates a valid RFC 4122 v4 UUID string
	s := uuid.NewString()
	if len(s) != 36 {
		fmt.Fprintf(os.Stderr, "FAIL: expected UUID string length 36, got %d (%s)\n", len(s), s)
		os.Exit(1)
	}
	parsed, err := uuid.Parse(s)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on uuid.NewString output: %v\n", err)
		os.Exit(1)
	}
	if parsed.Version() != 4 {
		fmt.Fprintf(os.Stderr, "FAIL: expected UUID version 4, got %d\n", parsed.Version())
		os.Exit(1)
	}
	if parsed.Variant() != uuid.RFC4122 {
		fmt.Fprintf(os.Stderr, "FAIL: expected RFC4122 variant, got %v\n", parsed.Variant())
		os.Exit(1)
	}

	// Assertion 2: uuid.Parse parses a valid canonical UUID string
	const knownValid = "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
	knownParsed, err := uuid.Parse(knownValid)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on known valid UUID: %v\n", err)
		os.Exit(1)
	}
	if knownParsed.String() != knownValid {
		fmt.Fprintf(os.Stderr, "FAIL: expected string %s, got %s\n", knownValid, knownParsed.String())
		os.Exit(1)
	}

	// Assertion 3: uuid.Parse returns an error for invalid UUID strings
	invalidInputs := []string{
		"",
		"not-a-uuid",
		"6ba7b810-9dad-11d1-80b4-00c04fd430cz",
		"6ba7b8109dad11d180b400c04fd430c8-extra",
	}
	for _, inv := range invalidInputs {
		if _, err := uuid.Parse(inv); err == nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected error parsing invalid UUID %q, got nil\n", inv)
			os.Exit(1)
		}
	}

	// Assertion 4: uuid.New returns a UUID value with version 4 and variant RFC4122
	u := uuid.New()
	if u == uuid.Nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.New returned Nil UUID\n")
		os.Exit(1)
	}
	if u.Version() != 4 {
		fmt.Fprintf(os.Stderr, "FAIL: expected version 4 from uuid.New, got %d\n", u.Version())
		os.Exit(1)
	}
	if u.Variant() != uuid.RFC4122 {
		fmt.Fprintf(os.Stderr, "FAIL: expected RFC4122 variant from uuid.New, got %v\n", u.Variant())
		os.Exit(1)
	}

	// Assertion 5: uuid.MustParse parses valid UUID string and panics on invalid input
	mustParsed := uuid.MustParse(knownValid)
	if mustParsed.String() != knownValid {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.MustParse produced incorrect string %s\n", mustParsed.String())
		os.Exit(1)
	}
	panicked := false
	func() {
		defer func() {
			if r := recover(); r != nil {
				panicked = true
			}
		}()
		uuid.MustParse("invalid-uuid-string")
	}()
	if !panicked {
		fmt.Fprintf(os.Stderr, "FAIL: expected uuid.MustParse to panic on invalid input\n")
		os.Exit(1)
	}

	fmt.Println("PASS: all contract assertions passed for pkg:golang/github.com/google/uuid@v1.6.0")
}