postcss-selector-parser 7.1.1: tag

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 postcss-selector-parser.tag in pkg:npm/postcss-selector-parser@7.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/postcss-selector-parser@7.1.1
Demonstrate these symbols/APIs:
  - postcss-selector-parser.tag

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:sha256:211dfedecab544ba32ea924b6895801c9adc3475a07d06ded7f5129a854729b1","contract":["parser.tag creates a Tag AST node with tag type, given value, and passes parser.isTag validation","parser.tag formats simple tag selector matching its value via toString","parser.tag supports namespace string prefix and formats as namespace|tag","parser.tag supports wildcard namespace string and boolean empty namespace prefix","parser.tag creates an empty Tag node when called without arguments","parser.tag nodes integrate with selector AST parsing, walking, and replacement","parser.isTag discriminates tag nodes from other AST node types but throws TypeError for null"],"goal":"verify postcss-selector-parser.tag in pkg:npm/postcss-selector-parser@7.1.1","kind":"HOW","packages":["pkg:npm/postcss-selector-parser@7.1.1"],"schemaVersion":1,"symbols":["postcss-selector-parser.tag"]},"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/postcss-selector-parser@7.1.1"],"schemaVersion":1,"subject":"pkg:npm/postcss-selector-parser@7.1.1","symbols":["postcss-selector-parser.tag"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-postcss-selector-parser-tag",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-postcss-selector-parser-tag",
      "version": "1.0.0",
      "dependencies": {
        "postcss-selector-parser": "7.1.1"
      }
    },
    "node_modules/cssesc": {
      "version": "3.0.0",
      "resolved": "https://registry.npmjs.org/cssesc/-/cssesc-3.0.0.tgz",
      "integrity": "sha512-/Tb/JcjK111nNScGob5MNtsntNM1aCNUDipB/TkwZFhyDrrE47SOx/18wF2bbjgc3ZzCSKW1T5nt5EbFoAz/Vg==",
      "license": "MIT",
      "bin": {
        "cssesc": "bin/cssesc"
      },
      "engines": {
        "node": ">=4"
      }
    },
    "node_modules/postcss-selector-parser": {
      "version": "7.1.1",
      "resolved": "https://registry.npmjs.org/postcss-selector-parser/-/postcss-selector-parser-7.1.1.tgz",
      "integrity": "sha512-orRsuYpJVw8LdAwqqLykBj9ecS5/cRHlI5+nvTo8LcCKmzDmqVORXtOIYEEQuL9D4BxtA1lm5isAqzQZCoQ6Eg==",
      "license": "MIT",
      "dependencies": {
        "cssesc": "^3.0.0",
        "util-deprecate": "^1.0.2"
      },
      "engines": {
        "node": ">=4"
      }
    },
    "node_modules/util-deprecate": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-postcss-selector-parser-tag",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "description": "Clean-room verification of postcss-selector-parser.tag in pkg:npm/postcss-selector-parser@7.1.1",
  "dependencies": {
    "postcss-selector-parser": "7.1.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify postcss-selector-parser.tag in pkg:npm/postcss-selector-parser@7.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/postcss-selector-parser@7.1.1"
  ],
  "symbols": [
    "postcss-selector-parser.tag"
  ]
}

import assert from 'node:assert/strict';
import parser from 'postcss-selector-parser';

const { tag, isTag, className } = parser;

// 1. parser.tag creates a Tag AST node with tag type, given value, and passes parser.isTag validation
{
  const node = tag({ value: 'button' });
  assert.equal(typeof tag, 'function');
  assert.equal(node.type, 'tag');
  assert.equal(node.value, 'button');
  assert.equal(isTag(node), true);
}

// 2. parser.tag formats simple tag selector matching its value via toString
{
  const node = tag({ value: 'div' });
  assert.equal(node.toString(), 'div');
  assert.equal(String(node), 'div');
}

// 3. parser.tag supports namespace string prefix and formats as namespace|tag
{
  const node = tag({ value: 'circle', namespace: 'svg' });
  assert.equal(node.type, 'tag');
  assert.equal(node.value, 'circle');
  assert.equal(node.namespace, 'svg');
  assert.equal(node.ns, 'svg');
  assert.equal(node.toString(), 'svg|circle');
}

// 4. parser.tag supports wildcard namespace string and boolean empty namespace prefix
{
  const wildcard = tag({ value: 'div', namespace: '*' });
  assert.equal(wildcard.namespace, '*');
  assert.equal(wildcard.toString(), '*|div');

  const emptyNs = tag({ value: 'span', namespace: true });
  assert.equal(emptyNs.namespace, true);
  assert.equal(emptyNs.toString(), '|span');
}

// 5. parser.tag creates an empty Tag node when called without arguments
{
  const empty = tag();
  assert.equal(empty.type, 'tag');
  assert.equal(empty.value, undefined);
  assert.equal(empty.toString(), 'undefined');
  assert.equal(isTag(empty), true);
}

// 6. parser.tag nodes integrate with selector AST parsing, walking, and replacement
{
  const ast = parser().astSync('main.hero > span');
  const found = [];
  ast.walkTags((node) => {
    found.push(node.value);
  });
  assert.deepEqual(found, ['main', 'span']);

  ast.walkTags((node) => {
    if (node.value === 'main') {
      node.replaceWith(tag({ value: 'section' }));
    }
  });
  assert.equal(ast.toString(), 'section.hero > span');
}

// 7. parser.isTag discriminates tag nodes from other AST node types but throws TypeError for null
{
  const tagNode = tag({ value: 'p' });
  const classNode = className({ value: 'intro' });
  assert.equal(isTag(tagNode), true);
  assert.equal(isTag(classNode), false);
  assert.equal(isTag(undefined), false);
  assert.equal(isTag('tag'), false);
  assert.throws(() => isTag(null), { name: 'TypeError' });
}