@bramus/specificity 2.4.2: calculate CSS selector specificity using @bramus/specificity

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: calculate CSS selector specificity using @bramus/specificity
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40bramus/specificity@2.4.2
Demonstrate these symbols/APIs:
  - calculate

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:sha256:35b4d4b93734a26f355703fdb2d3817d72092af6a08fc1fcc24acb96ead84232","contract":["Specificity.calculate parses single and comma-separated CSS selectors returning an array of Specificity instances","Specificity instance exposes a b c component getters representing ID class and type weights","Specificity instance provides toArray toObject toString and toJSON representation methods","Specificity instance throws error when attempting to mutate component weights directly","Specificity instances support comparison via isLessThan isGreaterThan and isEqualTo methods","Comparison and sorting utilities compare equals min max sortAsc sortDesc handle Specificity instances and objects"],"goal":"calculate CSS selector specificity using @bramus/specificity","kind":"HOW","packages":["pkg:npm/%40bramus/specificity@2.4.2"],"schemaVersion":1,"symbols":["calculate"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40bramus/specificity@2.4.2"],"schemaVersion":1,"subject":"pkg:npm/%40bramus/specificity@2.4.2","symbols":["calculate"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-specificity",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-specificity",
      "version": "1.0.0",
      "dependencies": {
        "@bramus/specificity": "2.4.2"
      }
    },
    "node_modules/@bramus/specificity": {
      "version": "2.4.2",
      "resolved": "https://registry.npmjs.org/@bramus/specificity/-/specificity-2.4.2.tgz",
      "integrity": "sha512-ctxtJ/eA+t+6q2++vj5j7FYX3nRu311q1wfYH3xjlLOsczhlhxAg2FWNUXhpGvAw3BWo1xBcvOV6/YLc2r5FJw==",
      "license": "MIT",
      "dependencies": {
        "css-tree": "^3.0.0"
      },
      "bin": {
        "specificity": "bin/cli.js"
      }
    },
    "node_modules/css-tree": {
      "version": "3.2.1",
      "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-3.2.1.tgz",
      "integrity": "sha512-X7sjQzceUhu1u7Y/ylrRZFU2FS6LRiFVp6rKLPg23y3x3c3DOKAwuXGDp+PAGjh6CSnCjYeAul8pcT8bAl+lSA==",
      "license": "MIT",
      "dependencies": {
        "mdn-data": "2.27.1",
        "source-map-js": "^1.2.1"
      },
      "engines": {
        "node": "^10 || ^12.20.0 || ^14.13.0 || >=15.0.0"
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    "node_modules/mdn-data": {
      "version": "2.27.1",
      "resolved": "https://registry.npmjs.org/mdn-data/-/mdn-data-2.27.1.tgz",
      "integrity": "sha512-9Yubnt3e8A0OKwxYSXyhLymGW4sCufcLG6VdiDdUGVkPhpqLxlvP5vl1983gQjJl3tqbrM731mjaZaP68AgosQ==",
      "license": "CC0-1.0"
    },
    "node_modules/source-map-js": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
      "integrity": "sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==",
      "license": "BSD-3-Clause",
      "engines": {
        "node": ">=0.10.0"
      }
    }
  }
}

{
  "name": "sample-specificity",
  "version": "1.0.0",
  "private": true,
  "description": "Calculate CSS selector specificity using @bramus/specificity",
  "type": "module",
  "main": "src/index.js",
  "dependencies": {
    "@bramus/specificity": "2.4.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "calculate CSS selector specificity using @bramus/specificity",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40bramus/specificity@2.4.2"
  ],
  "symbols": [
    "calculate"
  ]
}

import Specificity from '@bramus/specificity';
import { calculate } from '@bramus/specificity/core';
import { compare, equals, greaterThan, lessThan } from '@bramus/specificity/compare';
import { min, max } from '@bramus/specificity/filter';
import { sortAsc, sortDesc } from '@bramus/specificity/sort';

/**
 * Calculate the specificity for one or more CSS selectors (comma-separated).
 *
 * @param {string} selector - CSS selector string.
 * @returns {Array<Specificity>} Array of Specificity instances.
 */
export function calculateSpecificity(selector) {
  return Specificity.calculate(selector);
}

/**
 * Compare two Specificity instances or {a, b, c} objects.
 *
 * @param {Specificity|object} s1 - First specificity.
 * @param {Specificity|object} s2 - Second specificity.
 * @returns {number} Negative if s1 < s2, positive if s1 > s2, 0 if equal.
 */
export function compareSpecificity(s1, s2) {
  return compare(s1, s2);
}

/**
 * Check if two specificities are equal.
 *
 * @param {Specificity|object} s1
 * @param {Specificity|object} s2
 * @returns {boolean}
 */
export function isSpecificityEqual(s1, s2) {
  return equals(s1, s2);
}

/**
 * Check if the first specificity is greater than the second.
 *
 * @param {Specificity|object} s1
 * @param {Specificity|object} s2
 * @returns {boolean}
 */
export function isSpecificityGreaterThan(s1, s2) {
  return greaterThan(s1, s2);
}

/**
 * Check if the first specificity is less than the second.
 *
 * @param {Specificity|object} s1
 * @param {Specificity|object} s2
 * @returns {boolean}
 */
export function isSpecificityLessThan(s1, s2) {
  return lessThan(s1, s2);
}

/**
 * Find the minimum specificity from multiple arguments.
 *
 * @param {...(Specificity|object)} specificities
 * @returns {Specificity|object}
 */
export function minSpecificity(...specificities) {
  return min(...specificities);
}

/**
 * Find the maximum specificity from multiple arguments.
 *
 * @param {...(Specificity|object)} specificities
 * @returns {Specificity|object}
 */
export function maxSpecificity(...specificities) {
  return max(...specificities);
}

/**
 * Sort specificities in ascending order.
 *
 * @param {...(Specificity|object)} specificities
 * @returns {Array<Specificity|object>}
 */
export function sortSpecificityAsc(...specificities) {
  return sortAsc(...specificities);
}

/**
 * Sort specificities in descending order.
 *
 * @param {...(Specificity|object)} specificities
 * @returns {Array<Specificity|object>}
 */
export function sortSpecificityDesc(...specificities) {
  return sortDesc(...specificities);
}

export {
  Specificity,
  calculate,
  compare,
  equals,
  greaterThan,
  lessThan,
  min,
  max,
  sortAsc,
  sortDesc,
};

import assert from 'node:assert';
import {
  Specificity,
  calculate,
  calculateSpecificity,
  compare,
  compareSpecificity,
  equals,
  isSpecificityEqual,
  greaterThan,
  isSpecificityGreaterThan,
  lessThan,
  isSpecificityLessThan,
  min,
  minSpecificity,
  max,
  maxSpecificity,
  sortAsc,
  sortSpecificityAsc,
  sortDesc,
  sortSpecificityDesc,
} from '../src/index.js';

// 1. Verify exports
assert.strictEqual(typeof Specificity, 'function', 'Specificity should be a class constructor');
assert.strictEqual(typeof Specificity.calculate, 'function', 'Specificity.calculate should be a static method');
assert.strictEqual(typeof calculate, 'function', 'calculate should be exported');
assert.strictEqual(typeof calculateSpecificity, 'function', 'calculateSpecificity helper should be a function');
assert.strictEqual(typeof compare, 'function', 'compare should be exported');
assert.strictEqual(typeof equals, 'function', 'equals should be exported');
assert.strictEqual(typeof greaterThan, 'function', 'greaterThan should be exported');
assert.strictEqual(typeof lessThan, 'function', 'lessThan should be exported');
assert.strictEqual(typeof min, 'function', 'min should be exported');
assert.strictEqual(typeof max, 'function', 'max should be exported');
assert.strictEqual(typeof sortAsc, 'function', 'sortAsc should be exported');
assert.strictEqual(typeof sortDesc, 'function', 'sortDesc should be exported');

// 2. Specificity.calculate parses single CSS selectors
const singleId = Specificity.calculate('#main-header');
assert.strictEqual(Array.isArray(singleId), true, 'calculate should return an array');
assert.strictEqual(singleId.length, 1, 'Single selector should yield array of length 1');
assert.strictEqual(singleId[0].a, 1);
assert.strictEqual(singleId[0].b, 0);
assert.strictEqual(singleId[0].c, 0);
assert.strictEqual(singleId[0].toString(), '(1,0,0)');
assert.deepStrictEqual(singleId[0].toArray(), [1, 0, 0]);
assert.deepStrictEqual(singleId[0].toObject(), { a: 1, b: 0, c: 0 });

// 3. Specificity.calculate parses comma-separated selector lists
const list = calculateSpecificity('header:where(#top) nav li:nth-child(2n), #doormat');
assert.strictEqual(list.length, 2, 'Comma-separated selector should yield 2 items');

// First selector: header (c=1), :where(#top) (0), nav (c=1), li (c=1), :nth-child(2n) (b=1) -> (0, 1, 3)
const first = list[0];
assert.strictEqual(first.a, 0);
assert.strictEqual(first.b, 1);
assert.strictEqual(first.c, 3);
assert.strictEqual(first.toString(), '(0,1,3)');
assert.deepStrictEqual(first.toArray(), [0, 1, 3]);
assert.deepStrictEqual(first.toObject(), { a: 0, b: 1, c: 3 });
assert.strictEqual(first.selectorString(), 'header:where(#top) nav li:nth-child(2n)');

// Second selector: #doormat -> (1, 0, 0)
const second = list[1];
assert.strictEqual(second.a, 1);
assert.strictEqual(second.b, 0);
assert.strictEqual(second.c, 0);
assert.strictEqual(second.toString(), '(1,0,0)');
assert.strictEqual(second.selectorString(), '#doormat');

// 4. toJSON representation
const jsonOutput = first.toJSON();
assert.strictEqual(jsonOutput.selector, 'header:where(#top) nav li:nth-child(2n)');
assert.deepStrictEqual(jsonOutput.asObject, { a: 0, b: 1, c: 3 });
assert.deepStrictEqual(jsonOutput.asArray, [0, 1, 3]);
assert.strictEqual(jsonOutput.asString, '(0,1,3)');

// 5. Immutability: Mutating a, b, or c throws
assert.throws(() => {
  first.a = 2;
}, /Manipulating a Specificity instance is not allowed/);
assert.throws(() => {
  first.b = 2;
}, /Manipulating a Specificity instance is not allowed/);
assert.throws(() => {
  first.c = 2;
}, /Manipulating a Specificity instance is not allowed/);

// 6. Instance comparison methods
assert.strictEqual(first.isLessThan(second), true, '(0,1,3) should be less than (1,0,0)');
assert.strictEqual(second.isGreaterThan(first), true, '(1,0,0) should be greater than (0,1,3)');
assert.strictEqual(first.isEqualTo(first), true, 'first should equal itself');
assert.strictEqual(first.isEqualTo(second), false, 'first should not equal second');

// 7. Utility comparisons (functions and static methods)
assert.strictEqual(isSpecificityLessThan(first, second), true);
assert.strictEqual(isSpecificityGreaterThan(second, first), true);
assert.strictEqual(isSpecificityEqual(first, { a: 0, b: 1, c: 3 }), true);
assert.strictEqual(compareSpecificity(first, second) < 0, true);
assert.strictEqual(compareSpecificity(second, first) > 0, true);
assert.strictEqual(compareSpecificity(first, first), 0);

// 8. Filter and Sort utilities
const lowest = minSpecificity(second, first);
assert.strictEqual(lowest.toString(), '(0,1,3)');

const highest = maxSpecificity(second, first);
assert.strictEqual(highest.toString(), '(1,0,0)');

const sortedAsc = sortSpecificityAsc(second, first);
assert.strictEqual(sortedAsc[0].toString(), '(0,1,3)');
assert.strictEqual(sortedAsc[1].toString(), '(1,0,0)');

const sortedDesc = sortSpecificityDesc(first, second);
assert.strictEqual(sortedDesc[0].toString(), '(1,0,0)');
assert.strictEqual(sortedDesc[1].toString(), '(0,1,3)');

// Static methods on Specificity class
assert.strictEqual(Specificity.min(second, first).toString(), '(0,1,3)');
assert.strictEqual(Specificity.max(second, first).toString(), '(1,0,0)');

console.log('Contract tests passed successfully.');