dom-accessibility-api 0.6.3: computeAccessibleDescription

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 dom-accessibility-api.computeAccessibleDescription in pkg:npm/dom-accessibility-api@0.6.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/dom-accessibility-api@0.6.3
Demonstrate these symbols/APIs:
  - dom-accessibility-api.computeAccessibleDescription

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:sha256:5abd84d221cbb6cf707ffd74f125bf21002975a45fbb0f4fd817ea5d9f3a7da7","contract":["computeAccessibleDescription returns the accessible description of an element derived from aria-describedby attribute referencing another element","computeAccessibleDescription computes space-separated description from multiple IDs in aria-describedby attribute","computeAccessibleDescription falls back to aria-description attribute when aria-describedby is not present","computeAccessibleDescription falls back to title attribute when neither aria-describedby nor aria-description is present","computeAccessibleDescription prioritizes aria-describedby over aria-description and title","computeAccessibleDescription prioritizes aria-description over title attribute","computeAccessibleDescription returns empty string when no description source is present","computeAccessibleDescription accepts custom getComputedStyle function in options"],"goal":"verify dom-accessibility-api.computeAccessibleDescription in pkg:npm/dom-accessibility-api@0.6.3","kind":"HOW","packages":["pkg:npm/dom-accessibility-api@0.6.3"],"schemaVersion":1,"symbols":["dom-accessibility-api.computeAccessibleDescription"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/dom-accessibility-api@0.6.3"],"schemaVersion":1,"subject":"pkg:npm/dom-accessibility-api@0.6.3","symbols":["dom-accessibility-api.computeAccessibleDescription"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-dom-accessibility-api",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-dom-accessibility-api",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "dom-accessibility-api": "0.6.3"
      }
    },
    "node_modules/dom-accessibility-api": {
      "version": "0.6.3",
      "resolved": "https://registry.npmjs.org/dom-accessibility-api/-/dom-accessibility-api-0.6.3.tgz",
      "integrity": "sha512-7ZgogeTnjuHbo+ct10G9Ffp0mif17idi0IyWNVA/wcwcm7NPOD/WEHVP3n7n3MhXqxoIYm8d6MuZohYWIZ4T3w==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-dom-accessibility-api",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "dependencies": {
    "dom-accessibility-api": "0.6.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify dom-accessibility-api.computeAccessibleDescription in pkg:npm/dom-accessibility-api@0.6.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/dom-accessibility-api@0.6.3"
  ],
  "symbols": [
    "dom-accessibility-api.computeAccessibleDescription"
  ]
}

import assert from 'node:assert/strict';
import { computeAccessibleDescription } from 'dom-accessibility-api';

function createDocument() {
  const elementsById = new Map();
  const doc = {
    defaultView: {
      getComputedStyle: () => ({
        getPropertyValue: () => '',
      }),
    },
    getElementById: (id) => elementsById.get(id) || null,
  };

  class MockElement {
    constructor(tag, attrs = {}, text = '') {
      this.nodeType = 1;
      this.ELEMENT_NODE = 1;
      this.TEXT_NODE = 3;
      this.localName = tag.toLowerCase();
      this.tagName = tag.toUpperCase();
      this.nodeName = tag.toUpperCase();
      this.attributes = { ...attrs };
      this.childNodes = [];
      this.parentNode = null;
      this.ownerDocument = doc;

      if (attrs.id) {
        elementsById.set(attrs.id, this);
      }

      if (text) {
        const textNode = {
          nodeType: 3,
          TEXT_NODE: 3,
          ELEMENT_NODE: 1,
          nodeName: '#text',
          nodeValue: text,
          textContent: text,
          childNodes: [],
          parentNode: this,
          ownerDocument: doc,
        };
        this.childNodes.push(textNode);
      }
    }

    hasAttribute(name) {
      return Object.prototype.hasOwnProperty.call(this.attributes, name);
    }

    getAttribute(name) {
      return this.hasAttribute(name) ? this.attributes[name] : null;
    }

    getAttributeNode(name) {
      if (this.hasAttribute(name)) {
        return { value: this.attributes[name], specified: true };
      }
      return null;
    }

    getRootNode() {
      return doc;
    }
  }

  return { doc, MockElement, elementsById };
}

// 1. computeAccessibleDescription returns the accessible description of an element derived from aria-describedby attribute referencing another element
{
  const { MockElement } = createDocument();
  new MockElement('span', { id: 'desc1' }, 'Descriptive helper text');
  const btn = new MockElement('button', { 'aria-describedby': 'desc1' });
  const result = computeAccessibleDescription(btn);
  assert.equal(result, 'Descriptive helper text');
}

// 2. computeAccessibleDescription computes space-separated description from multiple IDs in aria-describedby attribute
{
  const { MockElement } = createDocument();
  new MockElement('span', { id: 'part1' }, 'First section.');
  new MockElement('span', { id: 'part2' }, 'Second section.');
  const input = new MockElement('input', { 'aria-describedby': 'part1 part2' });
  const result = computeAccessibleDescription(input);
  assert.equal(result, 'First section. Second section.');
}

// 3. computeAccessibleDescription falls back to aria-description attribute when aria-describedby is not present
{
  const { MockElement } = createDocument();
  const el = new MockElement('div', { 'aria-description': 'Direct ARIA description' });
  const result = computeAccessibleDescription(el);
  assert.equal(result, 'Direct ARIA description');
}

// 4. computeAccessibleDescription falls back to title attribute when neither aria-describedby nor aria-description is present
{
  const { MockElement } = createDocument();
  const el = new MockElement('a', { title: 'Hover title description' });
  const result = computeAccessibleDescription(el);
  assert.equal(result, 'Hover title description');
}

// 5. computeAccessibleDescription prioritizes aria-describedby over aria-description and title
{
  const { MockElement } = createDocument();
  new MockElement('span', { id: 'primary-desc' }, 'Primary describedby text');
  const el = new MockElement('button', {
    'aria-describedby': 'primary-desc',
    'aria-description': 'Ignored aria-description',
    title: 'Ignored title',
  });
  const result = computeAccessibleDescription(el);
  assert.equal(result, 'Primary describedby text');
}

// 6. computeAccessibleDescription prioritizes aria-description over title attribute
{
  const { MockElement } = createDocument();
  const el = new MockElement('button', {
    'aria-description': 'Aria description takes precedence',
    title: 'Ignored title',
  });
  const result = computeAccessibleDescription(el);
  assert.equal(result, 'Aria description takes precedence');
}

// 7. computeAccessibleDescription returns empty string when no description source is present
{
  const { MockElement } = createDocument();
  const el = new MockElement('div', {});
  const result = computeAccessibleDescription(el);
  assert.equal(result, '');
}

// 8. computeAccessibleDescription accepts custom getComputedStyle function in options
{
  const { MockElement } = createDocument();
  new MockElement('span', { id: 'custom-style-desc' }, 'Custom styled text');
  const el = new MockElement('button', { 'aria-describedby': 'custom-style-desc' });
  let customStyleCalled = false;
  const result = computeAccessibleDescription(el, {
    getComputedStyle: () => {
      customStyleCalled = true;
      return { getPropertyValue: () => '' };
    },
  });
  assert.equal(result, 'Custom styled text');
  assert.equal(customStyleCalled, true);
}

console.log('All dom-accessibility-api.computeAccessibleDescription contract tests passed.');