github.com/google/uuid v1.6.0: Generate and parse UUIDv4 strings with google/uuid

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 UUIDv4 strings with google/uuid
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/uuid@v1.6.0
Demonstrate these symbols/APIs:
  - NewString
  - Parse

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:sha256:214a1ec8d69c4cc898588e383e7d0733b1c071477ce34301355261501c5a4e40","contract":["uuid.NewString generates a non-empty 36-character hyphenated UUID string","uuid.NewString produces distinct unique UUID strings across repeated invocations","uuid.Parse successfully parses standard 36-character UUID strings generated by NewString","uuid.Parse successfully decodes UUID version 4 and RFC4122 variant from NewString output","uuid.Parse parses 32-character hexadecimal UUID strings without hyphens","uuid.Parse parses curly braced UUID strings","uuid.Parse parses URN formatted UUID strings","uuid.Parse returns an error when given invalid or malformed UUID strings","uuid.NewString and uuid.Parse round-trip accurately preserves byte representation"],"goal":"Generate and parse UUIDv4 strings with google/uuid","kind":"HOW","packages":["pkg:golang/github.com/google/uuid@v1.6.0"],"schemaVersion":1,"symbols":["NewString","Parse"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","ecosystem":"golang","language":"go","os":"windows","osVersionBucket":"11","packageManager":"go","packageManagerVersion":"1.26.5","runtime":"go","runtimeVersion":"1.26.5","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/google/uuid@v1.6.0"],"schemaVersion":1,"symbols":["NewString","Parse"],"verifierAdapter":"golang@1"}

module sample

go 1.22.0

require github.com/google/uuid v1.6.0

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"
	"log"

	"github.com/google/uuid"
)

// GenerateUUIDString generates a new random UUID v4 formatted as standard 36-character string.
func GenerateUUIDString() string {
	return uuid.NewString()
}

// ParseUUID parses a UUID string into a uuid.UUID value.
func ParseUUID(s string) (uuid.UUID, error) {
	return uuid.Parse(s)
}

func main() {
	idStr := GenerateUUIDString()
	fmt.Printf("Generated UUID string: %s\n", idStr)

	parsed, err := ParseUUID(idStr)
	if err != nil {
		log.Fatalf("Failed to parse UUID: %v\n", err)
	}
	fmt.Printf("Parsed UUID: %s (Version: %d, Variant: %s)\n", parsed.String(), parsed.Version(), parsed.Variant())
}

{
  "schemaVersion": 1,
  "goal": "Generate and parse UUIDv4 strings with google/uuid",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/google/uuid@v1.6.0"
  ],
  "symbols": [
    "NewString",
    "Parse"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"
	"regexp"

	"github.com/google/uuid"
)

func main() {
	// Assertion 1: uuid.NewString generates a non-empty 36-character hyphenated UUID string
	str1 := uuid.NewString()
	if len(str1) != 36 {
		fmt.Fprintf(os.Stderr, "FAIL: expected 36 characters, got %d for %q\n", len(str1), str1)
		os.Exit(1)
	}
	matched, err := regexp.MatchString("^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$", str1)
	if err != nil || !matched {
		fmt.Fprintf(os.Stderr, "FAIL: NewString did not match canonical UUIDv4 regex: %q\n", str1)
		os.Exit(1)
	}

	// Assertion 2: uuid.NewString produces distinct unique UUID strings across repeated invocations
	str2 := uuid.NewString()
	if str1 == str2 {
		fmt.Fprintf(os.Stderr, "FAIL: successive NewString calls produced duplicate UUID: %s\n", str1)
		os.Exit(1)
	}

	// Assertion 3: uuid.Parse successfully parses standard 36-character UUID strings generated by NewString
	parsed1, err := uuid.Parse(str1)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on NewString output %q: %v\n", str1, err)
		os.Exit(1)
	}
	if parsed1.String() != str1 {
		fmt.Fprintf(os.Stderr, "FAIL: parsed string mismatch: got %s, want %s\n", parsed1.String(), str1)
		os.Exit(1)
	}

	// Assertion 4: uuid.Parse successfully decodes UUID version 4 and RFC4122 variant from NewString output
	if parsed1.Version() != 4 {
		fmt.Fprintf(os.Stderr, "FAIL: expected UUID version 4, got %d\n", parsed1.Version())
		os.Exit(1)
	}
	if parsed1.Variant() != uuid.RFC4122 {
		fmt.Fprintf(os.Stderr, "FAIL: expected RFC4122 variant, got %v\n", parsed1.Variant())
		os.Exit(1)
	}

	// Assertion 5: uuid.Parse parses 32-character hexadecimal UUID strings without hyphens
	hexStr := "6ba7b8109dad11d180b400c04fd430c8"
	parsedHex, err := uuid.Parse(hexStr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on hex string %q: %v\n", hexStr, err)
		os.Exit(1)
	}
	if parsedHex.String() != "6ba7b810-9dad-11d1-80b4-00c04fd430c8" {
		fmt.Fprintf(os.Stderr, "FAIL: hex parsed UUID string mismatch: got %s\n", parsedHex.String())
		os.Exit(1)
	}

	// Assertion 6: uuid.Parse parses curly braced UUID strings
	bracedStr := "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}"
	parsedBraced, err := uuid.Parse(bracedStr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on braced string %q: %v\n", bracedStr, err)
		os.Exit(1)
	}
	if parsedBraced != parsedHex {
		fmt.Fprintf(os.Stderr, "FAIL: braced parsed UUID mismatch\n")
		os.Exit(1)
	}

	// Assertion 7: uuid.Parse parses URN formatted UUID strings
	urnStr := "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
	parsedURN, err := uuid.Parse(urnStr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: uuid.Parse failed on URN string %q: %v\n", urnStr, err)
		os.Exit(1)
	}
	if parsedURN != parsedHex {
		fmt.Fprintf(os.Stderr, "FAIL: URN parsed UUID mismatch\n")
		os.Exit(1)
	}

	// Assertion 8: uuid.Parse returns an error when given invalid or malformed UUID strings
	invalidSamples := []string{
		"",
		"invalid-uuid-string",
		"6ba7b810-9dad-11d1-80b4-00c04fd430c",     // 35 chars
		"6ba7b810-9dad-11d1-80b4-00c04fd430c89",    // 37 chars
		"6ba7b810-9dad-11d1-80b4-00c04fd430cg",    // invalid hex 'g'
		"{6ba7b810-9dad-11d1-80b4-00c04fd430c8",    // unmatched brace
	}
	for _, inv := range invalidSamples {
		if _, err := uuid.Parse(inv); err == nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected error for invalid UUID string %q, got nil\n", inv)
			os.Exit(1)
		}
	}

	// Assertion 9: uuid.NewString and uuid.Parse round-trip accurately preserves byte representation
	origStr := uuid.NewString()
	parsedRound, err := uuid.Parse(origStr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: round-trip parse error: %v\n", err)
		os.Exit(1)
	}
	if parsedRound.String() != origStr {
		fmt.Fprintf(os.Stderr, "FAIL: round-trip string mismatch: got %s, want %s\n", parsedRound.String(), origStr)
		os.Exit(1)
	}
	var rawBytes [16]byte
	copy(rawBytes[:], parsedRound[:])
	if !bytes.Equal(parsedRound[:], rawBytes[:]) {
		fmt.Fprintf(os.Stderr, "FAIL: round-trip byte mismatch\n")
		os.Exit(1)
	}

	fmt.Println("PASS: all contract assertions passed for NewString and Parse")
}