github.com/peterbourgon/diskv/v3 v3.0.1: New

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 github.com/peterbourgon/diskv/v3.New in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1
Demonstrate these symbols/APIs:
  - github.com/peterbourgon/diskv/v3.New

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:sha256:5ec7b55cc92c45a693d1c23f5a752603e20204da6aa034d532e57405cf4ff675","contract":["diskv.New initializes a Diskv store with specified Options","Diskv.Write and Diskv.Read persist and retrieve byte slice values by key","Diskv.Has returns true for present keys and false for missing keys","Diskv.Erase deletes a key and its associated value from the store","Diskv.EraseAll removes all stored keys and data"],"goal":"verify github.com/peterbourgon/diskv/v3.New in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1","kind":"HOW","packages":["pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1"],"schemaVersion":1,"symbols":["github.com/peterbourgon/diskv/v3.New"]},"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/github.com/peterbourgon/diskv/v3@v3.0.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1","symbols":["github.com/peterbourgon/diskv/v3.New"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/peterbourgon/diskv/v3 v3.0.1

require github.com/google/btree v1.0.0 // indirect

github.com/google/btree v1.0.0 h1:0udJVsspx3VBr5FwtLhQQtuAsVc79tTq0ocGIPAU6qo=
github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
github.com/peterbourgon/diskv/v3 v3.0.1 h1:x06SQA46+PKIUftmEujdwSEpIx8kR+M9eLYsUxeYveU=
github.com/peterbourgon/diskv/v3 v3.0.1/go.mod h1:kJ5Ny7vLdARGU3WUuy6uzO6T0nb/2gWcT1JiBvRmb5o=

package main

import (
	"fmt"
	"os"

	"github.com/peterbourgon/diskv/v3"
)

func main() {
	tempDir, err := os.MkdirTemp("", "diskv-demo-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tempDir)

	flatTransform := func(s string) []string {
		return []string{}
	}

	d := diskv.New(diskv.Options{
		BasePath:     tempDir,
		Transform:    flatTransform,
		CacheSizeMax: 1024 * 1024,
	})

	key := "sample-key"
	val := []byte("hello, diskv")

	if err := d.Write(key, val); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write key: %v\n", err)
		os.Exit(1)
	}

	readVal, err := d.Read(key)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to read key: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Read key %q: %s\n", key, string(readVal))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/peterbourgon/diskv/v3.New in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1"
  ],
  "symbols": [
    "github.com/peterbourgon/diskv/v3.New"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"

	"github.com/peterbourgon/diskv/v3"
)

func main() {
	tempDir, err := os.MkdirTemp("", "diskv-contract-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "setup failed: unable to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tempDir)

	flatTransform := func(s string) []string {
		return []string{}
	}

	// 1. diskv.New initializes a Diskv store with specified Options
	d := diskv.New(diskv.Options{
		BasePath:     tempDir,
		Transform:    flatTransform,
		CacheSizeMax: 1024 * 1024,
	})
	if d == nil {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: diskv.New returned nil\n")
		os.Exit(1)
	}

	// 2. Diskv.Write and Diskv.Read persist and retrieve byte slice values by key
	key1 := "test-key-1"
	val1 := []byte("stored payload bytes")
	if err := d.Write(key1, val1); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: d.Write returned error: %v\n", err)
		os.Exit(1)
	}
	gotVal, err := d.Read(key1)
	if err != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: d.Read returned error: %v\n", err)
		os.Exit(1)
	}
	if !bytes.Equal(gotVal, val1) {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected %q, got %q\n", string(val1), string(gotVal))
		os.Exit(1)
	}

	// 3. Diskv.Has returns true for present keys and false for missing keys
	if !d.Has(key1) {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: d.Has(%q) returned false for existing key\n", key1)
		os.Exit(1)
	}
	if d.Has("non-existent-key") {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: d.Has returned true for non-existent key\n")
		os.Exit(1)
	}

	// 4. Diskv.Erase deletes a key and its associated value from the store
	if err := d.Erase(key1); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: d.Erase returned error: %v\n", err)
		os.Exit(1)
	}
	if d.Has(key1) {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: key still present after d.Erase\n")
		os.Exit(1)
	}
	if _, err := d.Read(key1); err == nil {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: d.Read succeeded after key erased\n")
		os.Exit(1)
	}

	// 5. Diskv.EraseAll removes all stored keys and data
	if err := d.Write("bulk-key-a", []byte("value-a")); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 5 setup failed: %v\n", err)
		os.Exit(1)
	}
	if err := d.Write("bulk-key-b", []byte("value-b")); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 5 setup failed: %v\n", err)
		os.Exit(1)
	}
	if err := d.EraseAll(); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 5 failed: d.EraseAll returned error: %v\n", err)
		os.Exit(1)
	}
	if d.Has("bulk-key-a") || d.Has("bulk-key-b") {
		fmt.Fprintf(os.Stderr, "assertion 5 failed: keys still present after d.EraseAll\n")
		os.Exit(1)
	}

	fmt.Println("All contract assertions passed successfully.")
}