is-cidr 5.1.1: 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: verify is-cidr.v4 in pkg:npm/is-cidr@5.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/is-cidr@5.1.1
Demonstrate these symbols/APIs:
  - is-cidr.v4

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:sha256:4af3085e40040e1be795db7a656173623472a45c14e7b2bc72534b98a8402127","contract":["v4 is exported as both a named export and isCidr.v4","v4 returns true for valid IPv4 CIDR strings such as 10.0.0.0/8, 192.168.1.0/24, 0.0.0.0/0, and 255.255.255.255/32","v4 returns false for IPv6 CIDR strings, plain IPv4 addresses without prefix length, out-of-range prefixes or octets, and empty strings"],"goal":"verify is-cidr.v4 in pkg:npm/is-cidr@5.1.1","kind":"HOW","packages":["pkg:npm/is-cidr@5.1.1"],"schemaVersion":1,"symbols":["is-cidr.v4"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/is-cidr@5.1.1"],"schemaVersion":1,"subject":"pkg:npm/is-cidr@5.1.1","symbols":["is-cidr.v4"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-is-cidr-v4",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-is-cidr-v4",
      "version": "1.0.0",
      "dependencies": {
        "is-cidr": "5.1.1"
      }
    },
    "node_modules/cidr-regex": {
      "version": "4.1.3",
      "resolved": "https://registry.npmjs.org/cidr-regex/-/cidr-regex-4.1.3.tgz",
      "integrity": "sha512-86M1y3ZeQvpZkZejQCcS+IaSWjlDUC+ORP0peScQ4uEUFCZ8bEQVz7NlJHqysoUb6w3zCjx4Mq/8/2RHhMwHYw==",
      "license": "BSD-2-Clause",
      "dependencies": {
        "ip-regex": "^5.0.0"
      },
      "engines": {
        "node": ">=14"
      }
    },
    "node_modules/ip-regex": {
      "version": "5.0.0",
      "resolved": "https://registry.npmjs.org/ip-regex/-/ip-regex-5.0.0.tgz",
      "integrity": "sha512-fOCG6lhoKKakwv+C6KdsOnGvgXnmgfmp0myi3bcNwj3qfwPAxRKWEuFhvEFF7ceYIz6+1jRZ+yguLFAmUNPEfw==",
      "license": "MIT",
      "engines": {
        "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    },
    "node_modules/is-cidr": {
      "version": "5.1.1",
      "resolved": "https://registry.npmjs.org/is-cidr/-/is-cidr-5.1.1.tgz",
      "integrity": "sha512-AwzRMjtJNTPOgm7xuYZ71715z99t+4yRnSnSzgK5err5+heYi4zMuvmpUadaJ28+KCXCQo8CjUrKQZRWSPmqTQ==",
      "license": "BSD-2-Clause",
      "dependencies": {
        "cidr-regex": "^4.1.1"
      },
      "engines": {
        "node": ">=14"
      }
    }
  }
}

{
  "name": "sample-is-cidr-v4",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "dependencies": {
    "is-cidr": "5.1.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify is-cidr.v4 in pkg:npm/is-cidr@5.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/is-cidr@5.1.1"
  ],
  "symbols": [
    "is-cidr.v4"
  ]
}

import assert from "node:assert/strict";
import isCidr, { v4 } from "is-cidr";

assert.equal(v4, isCidr.v4);
assert.equal(v4("10.0.0.0/8"), true);
assert.equal(isCidr.v4("192.168.1.0/24"), true);
assert.equal(v4("255.255.255.255/32"), true);
assert.equal(v4("0.0.0.0/0"), true);

assert.equal(v4("2001:db8::/32"), false);
assert.equal(v4("10.0.0.1"), false);
assert.equal(v4("10.0.0.0/33"), false);
assert.equal(v4("256.0.0.0/8"), false);
assert.equal(v4(""), false);