yaml 2.9.0: Manage YAML nested collections and nodes with getIn, setIn, and deleteIn

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: Manage YAML nested collections and nodes with getIn, setIn, and deleteIn
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/yaml@2.9.0
Demonstrate these symbols/APIs:
  - Document
  - deleteIn
  - getIn
  - setIn
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@11.8.0
  - runtime: node@24.13.1

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:sha256:57bef6d696b68204675163aef685dce9a948825358dcf2b50606df055e55fe7f","constraints":{"executionContext":"node"},"contract":["Document getIn retrieves scalar values and nested AST collection nodes along a path","Document setIn updates existing values and creates nested intermediate collection maps","Document deleteIn removes keys or elements at nested paths and returns boolean status","Document getIn and setIn support zero-indexed paths for sequence elements","Document toString serializes AST modifications made via setIn and deleteIn while preserving comments"],"goal":"Manage YAML nested collections and nodes with getIn, setIn, and deleteIn","kind":"HOW","packages":["pkg:npm/yaml@2.9.0"],"schemaVersion":1,"symbols":["Document","deleteIn","getIn","setIn"]},"contractCommand":["node","test/contract.js"],"environment":{"arch":"x64","ecosystem":"npm","executionContext":"node","language":"javascript","moduleSystem":"cjs","os":"windows","osVersionBucket":"11","packageManager":"npm","runtime":"node","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/yaml@2.9.0"],"schemaVersion":1,"symbols":["Document","deleteIn","getIn","setIn"],"verifierAdapter":"node-typescript@1"}

const { Document, parseDocument } = require('yaml');

function createDocument(value) {
  return new Document(value);
}

function parseYaml(yamlString) {
  return parseDocument(yamlString);
}

function getValueIn(doc, path, keepScalar = false) {
  return doc.getIn(path, keepScalar);
}

function setValueIn(doc, path, value) {
  doc.setIn(path, value);
  return doc;
}

function removeValueIn(doc, path) {
  return doc.deleteIn(path);
}

module.exports = {
  Document,
  parseDocument,
  createDocument,
  parseYaml,
  getValueIn,
  setValueIn,
  removeValueIn
};

{
  "name": "sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample",
      "version": "1.0.0",
      "dependencies": {
        "yaml": "2.9.0"
      }
    },
    "node_modules/yaml": {
      "version": "2.9.0",
      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.9.0.tgz",
      "integrity": "sha512-2AvhNX3mb8zd6Zy7INTtSpl1F15HW6Wnqj0srWlkKLcpYl/gMIMJiyuGq2KeI2YFxUPjdlB+3Lc10seMLtL4cA==",
      "license": "ISC",
      "bin": {
        "yaml": "bin.mjs"
      },
      "engines": {
        "node": ">= 14.6"
      },
      "funding": {
        "url": "https://github.com/sponsors/eemeli"
      }
    }
  }
}

{
  "name": "sample",
  "version": "1.0.0",
  "private": true,
  "main": "index.js",
  "dependencies": {
    "yaml": "2.9.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "Manage YAML nested collections and nodes with getIn, setIn, and deleteIn",
  "kind": "HOW",
  "packages": [
    "pkg:npm/yaml@2.9.0"
  ],
  "symbols": [
    "Document",
    "deleteIn",
    "getIn",
    "setIn"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@11.8.0",
    "runtime": "node@24.13.1"
  }
}

const assert = require('assert');
const {
  Document,
  parseDocument,
  createDocument,
  parseYaml,
  getValueIn,
  setValueIn,
  removeValueIn
} = require('../index.js');

// 1. Document getIn retrieves scalar values and nested AST collection nodes along a path
const yamlText1 = 'server:\n  host: 127.0.0.1\n  port: 8080\n';
const doc1 = parseYaml(yamlText1);
assert.strictEqual(doc1.getIn(['server', 'host']), '127.0.0.1');
assert.strictEqual(getValueIn(doc1, ['server', 'port']), 8080);
assert.strictEqual(doc1.getIn(['nonexistent', 'path']), undefined);

// 2. Document setIn updates existing values and creates nested intermediate collection maps
const doc2 = new Document({ title: 'Config' });
doc2.setIn(['database', 'primary', 'port'], 5432);
setValueIn(doc2, ['database', 'primary', 'user'], 'admin');
assert.strictEqual(doc2.getIn(['database', 'primary', 'port']), 5432);
assert.strictEqual(doc2.getIn(['database', 'primary', 'user']), 'admin');

// 3. Document deleteIn removes keys or elements at nested paths and returns boolean status
const yamlText3 = 'services:\n  auth:\n    enabled: true\n    timeout: 30\n';
const doc3 = parseDocument(yamlText3);
const deleted1 = removeValueIn(doc3, ['services', 'auth', 'timeout']);
assert.strictEqual(deleted1, true);
assert.strictEqual(doc3.getIn(['services', 'auth', 'timeout']), undefined);
assert.strictEqual(doc3.getIn(['services', 'auth', 'enabled']), true);
const deleted2 = doc3.deleteIn(['services', 'unknown']);
assert.strictEqual(deleted2, false);

// 4. Document getIn and setIn support zero-indexed paths for sequence elements
const yamlText4 = 'pipeline:\n  stages:\n    - build\n    - test\n    - deploy\n';
const doc4 = parseDocument(yamlText4);
assert.strictEqual(doc4.getIn(['pipeline', 'stages', 1]), 'test');
doc4.setIn(['pipeline', 'stages', 1], 'integration-test');
assert.strictEqual(doc4.getIn(['pipeline', 'stages', 1]), 'integration-test');

// 5. Document toString serializes AST modifications made via setIn and deleteIn while preserving comments
const yamlText5 = '# Application configuration\napp:\n  name: service-a # main name\n  debug: true\n';
const doc5 = parseDocument(yamlText5);
doc5.setIn(['app', 'debug'], false);
doc5.setIn(['app', 'version'], '1.0.0');
doc5.deleteIn(['app', 'name']);
const serialized = doc5.toString();
assert.ok(serialized.includes('# Application configuration'));
assert.ok(serialized.includes('debug: false'));
assert.ok(serialized.includes('version: 1.0.0'));
assert.ok(!serialized.includes('service-a'));

console.log('PASS: all contract assertions passed for Document, getIn, setIn, and deleteIn');