diff 5.2.2

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:npm/diff@5.2.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/diff@5.2.2

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:sha256:2e51e6abdda4f45aa5a156fbda8c663739748b7fd13df9beabeb4438a4c53988","contract":["diffLines, diffWords, and diffChars return ordered change objects with value, count, added, and removed properties","diffJson canonicalizes object keys before line diffing and diffArrays diffs array elements without stringifying","createTwoFilesPatch produces a unified diff that parsePatch parses into hunks, applyPatch applies to reproduce new content, and reversePatch inverts to restore old content","structuredPatch returns structured hunk metadata and convertChangesToXML escapes HTML entities while wrapping insertions in \u003cins\u003e and deletions in \u003cdel\u003e"],"goal":"verify pkg:npm/diff@5.2.2","kind":"HOW","packages":["pkg:npm/diff@5.2.2"],"schemaVersion":1,"symbols":["diffLines","diffWords","diffChars","diffJson","diffArrays","createTwoFilesPatch","parsePatch","applyPatch","reversePatch","structuredPatch","convertChangesToXML"]},"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","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-diff",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-diff",
      "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",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "diff": "5.2.2"
  }
}

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

import {
  diffChars,
  diffWords,
  diffLines,
  diffJson,
  diffArrays,
  createTwoFilesPatch,
  parsePatch,
  applyPatch,
  reversePatch,
  structuredPatch,
  convertChangesToXML
} from 'diff';

export function compareLines(oldText, newText) {
  return diffLines(oldText, newText);
}

export function compareWords(oldText, newText) {
  return diffWords(oldText, newText);
}

export function compareChars(oldText, newText) {
  return diffChars(oldText, newText);
}

export function compareObjects(oldObj, newObj) {
  return diffJson(oldObj, newObj);
}

export function compareLists(oldArr, newArr) {
  return diffArrays(oldArr, newArr);
}

export function buildAndApplyPatch(oldFile, newFile, oldContent, newContent) {
  const patchText = createTwoFilesPatch(oldFile, newFile, oldContent, newContent, 'v1', 'v2');
  const parsed = parsePatch(patchText);
  const applied = applyPatch(oldContent, patchText);
  const reversed = reversePatch(parsed[0]);
  const reverted = applyPatch(applied, reversed);
  return { patchText, parsed, applied, reverted };
}

export function buildStructuredAndXml(oldText, newText) {
  const structured = structuredPatch('old.txt', 'new.txt', oldText, newText, '', '');
  const xml = convertChangesToXML(diffWords(oldText, newText));
  return { structured, xml };
}

import assert from 'node:assert/strict';
import {
  compareLines,
  compareWords,
  compareChars,
  compareObjects,
  compareLists,
  buildAndApplyPatch,
  buildStructuredAndXml
} from '../src/index.mjs';

// 1. Line diffing
const lineChanges = compareLines('alpha\nbeta\n', 'alpha\ngamma\n');
assert.equal(lineChanges.length, 3);
assert.equal(lineChanges[0].value, 'alpha\n');
assert.equal(Boolean(lineChanges[1].removed), true);
assert.equal(lineChanges[1].value, 'beta\n');
assert.equal(Boolean(lineChanges[2].added), true);
assert.equal(lineChanges[2].value, 'gamma\n');

// 2. Word and character diffing
const wordChanges = compareWords('hello world', 'hello brave world');
assert.equal(wordChanges.some((c) => c.added && c.value.includes('brave')), true);

const charChanges = compareChars('cat', 'car');
assert.equal(charChanges.length, 3);
assert.equal(charChanges[0].value, 'ca');
assert.equal(charChanges[1].removed, true);
assert.equal(charChanges[1].value, 't');
assert.equal(charChanges[2].added, true);
assert.equal(charChanges[2].value, 'r');

// 3. JSON and Array diffing
const jsonChanges = compareObjects({ b: 2, a: 1 }, { a: 1, b: 3 });
assert.equal(jsonChanges.some((c) => c.removed && c.value.includes('2')), true);
assert.equal(jsonChanges.some((c) => c.added && c.value.includes('3')), true);

const arrayChanges = compareLists(['x', 'y'], ['x', 'z']);
assert.deepEqual(arrayChanges, [
  { count: 1, value: ['x'] },
  { count: 1, added: undefined, removed: true, value: ['y'] },
  { count: 1, added: true, removed: undefined, value: ['z'] }
]);

// 4. Unified patch creation, parsing, application, and reversal
const oldContent = 'line1\nline2\nline3\n';
const newContent = 'line1\nline2-modified\nline3\n';
const { patchText, parsed, applied, reverted } = buildAndApplyPatch(
  'a.txt',
  'b.txt',
  oldContent,
  newContent
);
assert.equal(patchText.includes('--- a.txt'), true);
assert.equal(patchText.includes('+++ b.txt'), true);
assert.equal(parsed.length, 1);
assert.equal(parsed[0].hunks.length, 1);
assert.equal(applied, newContent);
assert.equal(reverted, oldContent);

// 5. Structured patch and XML conversion
const { structured, xml } = buildStructuredAndXml('foo & bar', 'foo & baz');
assert.equal(structured.hunks.length, 1);
assert.equal(xml, 'foo &amp; <del>bar</del><ins>baz</ins>');