diff 5.2.2: diffWords

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 diffWords in pkg:npm/diff@5.2.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/diff@5.2.2
Demonstrate these symbols/APIs:
  - diffWords

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:sha256:6ccc3b52b56c21bcd6c0b7a18638c90d4e7bdcdb47a6adda6714099d86aa89f5","contract":["diffWords returns ordered change objects with value, count, added, and removed properties for word-level insertions and deletions","diffWords ignores horizontal whitespace differences between unchanged words","diffWords supports case-insensitive word comparison when options.ignoreCase is true"],"goal":"verify diffWords in pkg:npm/diff@5.2.2","kind":"HOW","packages":["pkg:npm/diff@5.2.2"],"schemaVersion":1,"symbols":["diffWords"]},"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/diff@5.2.2"],"schemaVersion":1,"subject":"pkg:npm/diff@5.2.2","symbols":["diffWords"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-diff-words",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-diff-words",
      "version": "1.0.0",
      "dependencies": {
        "diff": "5.2.2"
      }
    },
    "node_modules/diff": {
      "version": "5.2.2",
      "resolved": "https://registry.npmjs.org/diff/-/diff-5.2.2.tgz",
      "integrity": "sha512-vtcDfH3TOjP8UekytvnHH1o1P4FcUdt4eQ1Y+Abap1tk/OB2MWQvcwS2ClCd1zuIhc3JKOx6p3kod8Vfys3E+A==",
      "license": "BSD-3-Clause",
      "engines": {
        "node": ">=0.3.1"
      }
    }
  }
}

{
  "name": "sample-diff-words",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "diff": "5.2.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify diffWords in pkg:npm/diff@5.2.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/diff@5.2.2"
  ],
  "symbols": [
    "diffWords"
  ]
}

import { diffWords } from 'diff';

export function computeWordDiff(oldText, newText, options = {}) {
  return diffWords(oldText, newText, options);
}

export function summarizeWordChanges(oldText, newText, options = {}) {
  const changes = diffWords(oldText, newText, options);
  const added = [];
  const removed = [];
  const unchanged = [];

  for (const part of changes) {
    if (part.added) {
      added.push(part.value);
    } else if (part.removed) {
      removed.push(part.value);
    } else {
      unchanged.push(part.value);
    }
  }

  return { changes, added, removed, unchanged };
}

import assert from 'node:assert/strict';
import { computeWordDiff, summarizeWordChanges } from '../src/index.mjs';

// 1. Basic word-level replacement preserves surrounding whitespace and order
const changes = computeWordDiff('the quick brown fox', 'the fast brown fox');
assert.equal(Array.isArray(changes), true);
assert.equal(changes.length, 4);
assert.equal(changes[0].value, 'the ');
assert.equal(Boolean(changes[0].added), false);
assert.equal(Boolean(changes[0].removed), false);

assert.equal(changes[1].value, 'quick');
assert.equal(changes[1].removed, true);
assert.equal(Boolean(changes[1].added), false);

assert.equal(changes[2].value, 'fast');
assert.equal(changes[2].added, true);
assert.equal(Boolean(changes[2].removed), false);

assert.equal(changes[3].value, ' brown fox');
assert.equal(Boolean(changes[3].added), false);
assert.equal(Boolean(changes[3].removed), false);

// 2. Horizontal whitespace differences between unchanged words are ignored by diffWords
const wsChanges = computeWordDiff('alpha   beta', 'alpha\tbeta');
assert.equal(wsChanges.length, 1);
assert.equal(Boolean(wsChanges[0].added), false);
assert.equal(Boolean(wsChanges[0].removed), false);

// 3. Case-insensitive word diffing via ignoreCase option
const caseSensitive = summarizeWordChanges('Hello World', 'hello world');
assert.equal(caseSensitive.removed.length > 0, true);
assert.equal(caseSensitive.added.length > 0, true);

const caseInsensitive = summarizeWordChanges('Hello World', 'hello world', {
  ignoreCase: true
});
assert.deepEqual(caseInsensitive.added, []);
assert.deepEqual(caseInsensitive.removed, []);
assert.equal(caseInsensitive.changes.length, 1);