github.com/google/uuid v1.6.0: FromBytes

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 pkg:golang/github.com/google/uuid@v1.6.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/uuid@v1.6.0
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:f30859e4a37bbcd1eae8cd7d8cabb6b192b9febcadf63709ed73553d0e8ebb60","contract":["uuid.FromBytes parses a valid 16-byte slice into a UUID without error","uuid.FromBytes preserves the exact byte sequence in round-trip conversion","uuid.FromBytes returns an error for byte slices with length other than 16 bytes"],"goal":"verify pkg:golang/github.com/google/uuid@v1.6.0","kind":"HOW","packages":["pkg:golang/github.com/google/uuid@v1.6.0"],"schemaVersion":1,"symbols":["github.com/google/uuid.FromBytes"]},"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":["github.com/google/uuid.FromBytes"],"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 sample

import (
	"fmt"

	"github.com/google/uuid"
)

// UUIDFromSlice converts a 16-byte slice into a UUID using uuid.FromBytes.
func UUIDFromSlice(b []byte) (uuid.UUID, error) {
	id, err := uuid.FromBytes(b)
	if err != nil {
		return uuid.Nil, fmt.Errorf("uuid.FromBytes failed: %w", err)
	}
	return id, nil
}

// UUIDToBytes returns a 16-byte copy of the underlying UUID bytes.
func UUIDToBytes(id uuid.UUID) []byte {
	b := make([]byte, 16)
	copy(b, id[:])
	return b
}

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

package main

import (
	"bytes"
	"fmt"
	"os"

	"sample"

	"github.com/google/uuid"
)

func main() {
	// Assertion 1: uuid.FromBytes parses a valid 16-byte slice into UUID
	rawBytes := []byte{
		0x6b, 0xa7, 0xb8, 0x10,
		0x9d, 0xad,
		0x11, 0xd1,
		0x80, 0xb4,
		0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8,
	}

	id, err := sample.UUIDFromSlice(rawBytes)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: UUIDFromSlice returned error for valid 16-byte slice: %v\n", err)
		os.Exit(1)
	}

	if id == uuid.Nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected non-nil UUID, got nil\n")
		os.Exit(1)
	}

	expectedStr := "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
	if id.String() != expectedStr {
		fmt.Fprintf(os.Stderr, "FAIL: string mismatch: got %s, want %s\n", id.String(), expectedStr)
		os.Exit(1)
	}

	// Assertion 2: uuid.FromBytes preserves the exact byte sequence in round-trip
	exportedBytes := sample.UUIDToBytes(id)
	if !bytes.Equal(exportedBytes, rawBytes) {
		fmt.Fprintf(os.Stderr, "FAIL: byte mismatch: got %x, want %x\n", exportedBytes, rawBytes)
		os.Exit(1)
	}

	// Assertion 3: uuid.FromBytes returns an error for invalid slice lengths
	invalidShort := []byte{0x01, 0x02, 0x03}
	if _, err := sample.UUIDFromSlice(invalidShort); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error for 3-byte slice, got nil\n")
		os.Exit(1)
	}

	invalidLong := make([]byte, 17)
	if _, err := sample.UUIDFromSlice(invalidLong); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error for 17-byte slice, got nil\n")
		os.Exit(1)
	}

	if _, err := uuid.FromBytes(nil); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error for nil slice, got nil\n")
		os.Exit(1)
	}

	fmt.Println("PASS: uuid.FromBytes contract passed")
}