fill-range 7.1.1: fill-range

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 fill-range in pkg:npm/fill-range@7.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/fill-range@7.1.1
Demonstrate these symbols/APIs:
  - fill-range
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:c9bad71e17ac0ad3dcc480b2a4898fb369e9c84a07b66fed3e338791c7854a9b","constraints":{"executionContext":"node"},"contract":["fill expands numerical integer ranges in ascending and descending order","fill expands numerical ranges with custom step increments","fill expands alphabetical character ranges in ascending and descending order","fill preserves zero-padding format when string inputs have leading zeros","fill transforms output values using a custom transform function","fill converts number ranges to string arrays when stringify option is enabled","fill generates regex range patterns when toRegex option is enabled","fill handles single-argument and invalid range options"],"goal":"verify fill-range in pkg:npm/fill-range@7.1.1","kind":"HOW","packages":["pkg:npm/fill-range@7.1.1"],"schemaVersion":1,"symbols":["fill-range"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/fill-range@7.1.1"],"schemaVersion":1,"subject":"pkg:npm/fill-range@7.1.1","symbols":["fill-range"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-fill-range",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-fill-range",
      "version": "1.0.0",
      "dependencies": {
        "fill-range": "7.1.1"
      }
    },
    "node_modules/fill-range": {
      "version": "7.1.1",
      "resolved": "https://registry.npmjs.org/fill-range/-/fill-range-7.1.1.tgz",
      "integrity": "sha512-YsGpe3WHLK8ZYi4tWDg2Jy3ebRz2rXowDxnld4bkQB00cc/1Zw9AWnC0i9ztDJitivtQvaI9KaLyKrc+hBW0yg==",
      "license": "MIT",
      "dependencies": {
        "to-regex-range": "^5.0.1"
      },
      "engines": {
        "node": ">=8"
      }
    },
    "node_modules/is-number": {
      "version": "7.0.0",
      "resolved": "https://registry.npmjs.org/is-number/-/is-number-7.0.0.tgz",
      "integrity": "sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==",
      "license": "MIT",
      "engines": {
        "node": ">=0.12.0"
      }
    },
    "node_modules/to-regex-range": {
      "version": "5.0.1",
      "resolved": "https://registry.npmjs.org/to-regex-range/-/to-regex-range-5.0.1.tgz",
      "integrity": "sha512-65P7iz6X5yEr1cwcgvQxbbIw7Uk3gOy5dIdtZ4rDveLqhrdJP+Li/Hx6tyK0NEb+2GCyneCMJiGqrADCSNk8sQ==",
      "license": "MIT",
      "dependencies": {
        "is-number": "^7.0.0"
      },
      "engines": {
        "node": ">=8.0"
      }
    }
  }
}

{
  "name": "sample-fill-range",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "fill-range": "7.1.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify fill-range in pkg:npm/fill-range@7.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/fill-range@7.1.1"
  ],
  "symbols": [
    "fill-range"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert/strict';
import fill from 'fill-range';

// 1. fill expands numerical integer ranges in ascending and descending order
{
  assert.deepEqual(fill(1, 5), [1, 2, 3, 4, 5]);
  assert.deepEqual(fill(5, 1), [5, 4, 3, 2, 1]);
  assert.deepEqual(fill(-2, 2), [-2, -1, 0, 1, 2]);
  assert.deepEqual(fill(0, 0), [0]);
}

// 2. fill expands numerical ranges with custom step increments
{
  assert.deepEqual(fill(1, 10, 2), [1, 3, 5, 7, 9]);
  assert.deepEqual(fill(10, 1, 2), [10, 8, 6, 4, 2]);
  assert.deepEqual(fill(1, 10, 3), [1, 4, 7, 10]);
  assert.deepEqual(fill(0, 20, 5), [0, 5, 10, 15, 20]);
}

// 3. fill expands alphabetical character ranges in ascending and descending order
{
  assert.deepEqual(fill('a', 'e'), ['a', 'b', 'c', 'd', 'e']);
  assert.deepEqual(fill('e', 'a'), ['e', 'd', 'c', 'b', 'a']);
  assert.deepEqual(fill('A', 'E', 2), ['A', 'C', 'E']);
  assert.deepEqual(fill('z', 'v', 2), ['z', 'x', 'v']);
}

// 4. fill preserves zero-padding format when string inputs have leading zeros
{
  assert.deepEqual(fill('01', '05'), ['01', '02', '03', '04', '05']);
  assert.deepEqual(fill('001', '005'), ['001', '002', '003', '004', '005']);
  assert.deepEqual(fill('01', '10', 2), ['01', '03', '05', '07', '09']);
  assert.deepEqual(fill('05', '01'), ['05', '04', '03', '02', '01']);
}

// 5. fill transforms output values using a custom transform function
{
  const result1 = fill(1, 3, (val) => String.fromCharCode(val + 64));
  assert.deepEqual(result1, ['A', 'B', 'C']);

  const result2 = fill(1, 3, (val) => val * 10);
  assert.deepEqual(result2, [10, 20, 30]);

  const result3 = fill(1, 3, { transform: (val, index) => `${index}:${val}` });
  assert.deepEqual(result3, ['0:1', '1:2', '2:3']);
}

// 6. fill converts number ranges to string arrays when stringify option is enabled
{
  assert.deepEqual(fill(1, 5, { stringify: true }), ['1', '2', '3', '4', '5']);
  assert.deepEqual(fill(-2, 2, { stringify: true }), ['-2', '-1', '0', '1', '2']);
}

// 7. fill generates regex range patterns when toRegex option is enabled
{
  assert.equal(fill(1, 5, { toRegex: true }), '[1-5]');
  assert.equal(fill('a', 'e', { toRegex: true }), '[a-e]');
  assert.equal(fill(1, 10, 2, { toRegex: true }), '1|3|5|7|9');
  assert.equal(fill('01', '05', { toRegex: true }), '0?[1-5]');
}

// 8. fill handles single-argument and invalid range options
{
  assert.deepEqual(fill(1), [1]);
  assert.deepEqual(fill('a'), ['a']);
  assert.deepEqual(fill(1, 'foo'), []);
  assert.throws(
    () => fill(1, 'foo', { strictRanges: true }),
    /^RangeError: Invalid range arguments:/
  );
  assert.throws(
    () => fill(1, 5, 'invalid_step', { strictRanges: true }),
    /^TypeError: Expected step "invalid_step" to be a number/
  );
}