@jridgewell/sourcemap-codec 1.5.5

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/%40jridgewell/sourcemap-codec@1.5.5
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40jridgewell/sourcemap-codec@1.5.5
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:c1eedf026b33995402c8d056c7b08cc18a5304922a99c0105de361b7e2eaadaf","constraints":{"executionContext":"node"},"contract":["decode parses VLQ encoded string mappings into multi-line arrays of 4-element coordinate segments","decode parses 1-element column segments and 5-element segments with source name indices","decode maps an empty string to a single line containing an empty segment array","decode and encode preserve empty lines represented by consecutive semicolons","decode tracks relative state deltas for source index, original line, and original column across lines","encode serializes nested coordinate segment arrays into VLQ encoded sourcemap mapping strings","encode and decode perform lossless roundtrips on complex multi-line sourcemap mappings"],"goal":"verify pkg:npm/%40jridgewell/sourcemap-codec@1.5.5","kind":"HOW","packages":["pkg:npm/%40jridgewell/sourcemap-codec@1.5.5"],"schemaVersion":1},"contractCommand":["node","test/contract.cjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40jridgewell/sourcemap-codec@1.5.5"],"schemaVersion":1,"subject":"pkg:npm/%40jridgewell/sourcemap-codec@1.5.5","verifierAdapter":"node-typescript@1"}

'use strict';

const { encode, decode } = require('@jridgewell/sourcemap-codec');

function decodeMappings(mappings) {
  return decode(mappings);
}

function encodeMappings(decoded) {
  return encode(decoded);
}

module.exports = {
  decode,
  encode,
  decodeMappings,
  encodeMappings,
};

{
  "name": "sample-sourcemap-codec",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-sourcemap-codec",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@jridgewell/sourcemap-codec": "1.5.5"
      }
    },
    "node_modules/@jridgewell/sourcemap-codec": {
      "version": "1.5.5",
      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
      "integrity": "sha512-cYQ9310grqxueWbl+WuIUIaiUaDcj7WOq5fVhEljNVgRfOUhY9fy2zTvfoqWsnebh8Sl70VScFbICvJnLKB0Og==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-sourcemap-codec",
  "version": "1.0.0",
  "private": true,
  "license": "MIT-0",
  "dependencies": {
    "@jridgewell/sourcemap-codec": "1.5.5"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40jridgewell/sourcemap-codec@1.5.5",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40jridgewell/sourcemap-codec@1.5.5"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

'use strict';

const assert = require('assert');
const { encode, decode, decodeMappings, encodeMappings } = require('../index.js');

function runContract() {
  // 1. decode parses VLQ encoded string mappings into multi-line arrays of 4-element coordinate segments
  const basicMappings = 'AAAA';
  const decodedBasic = decode(basicMappings);
  assert.deepStrictEqual(decodedBasic, [[[0, 0, 0, 0]]]);
  assert.strictEqual(encode(decodedBasic), basicMappings);
  assert.deepStrictEqual(decodeMappings(basicMappings), [[[0, 0, 0, 0]]]);

  // 2. decode parses 1-element column segments and 5-element segments with source name indices
  const singleSegment = 'A,C,C';
  const decodedSingle = decode(singleSegment);
  assert.deepStrictEqual(decodedSingle, [[[0], [1], [2]]]);
  assert.strictEqual(encode(decodedSingle), singleSegment);

  const fiveSegment = 'AAAAA';
  const decodedFive = decode(fiveSegment);
  assert.deepStrictEqual(decodedFive, [[[0, 0, 0, 0, 0]]]);
  assert.strictEqual(encode(decodedFive), fiveSegment);

  // 3. decode maps an empty string to a single line containing an empty segment array
  const emptyDecoded = decode('');
  assert.deepStrictEqual(emptyDecoded, [[]]);
  assert.strictEqual(encode([[]]), '');
  assert.strictEqual(encode([]), '');
  assert.strictEqual(encodeMappings([[]]), '');

  // 4. decode and encode preserve empty lines represented by consecutive semicolons
  const withEmptyLines = 'AAAA;;QAAT';
  const decodedEmptyLines = decode(withEmptyLines);
  assert.strictEqual(decodedEmptyLines.length, 3);
  assert.deepStrictEqual(decodedEmptyLines[0], [[0, 0, 0, 0]]);
  assert.deepStrictEqual(decodedEmptyLines[1], []);
  assert.deepStrictEqual(decodedEmptyLines[2], [[8, 0, 0, -9]]);
  assert.strictEqual(encode(decodedEmptyLines), withEmptyLines);

  // 5. decode tracks relative state deltas for source index, original line, and original column across lines
  const multiSegment = 'AAAA,SAAS;QAAT';
  const decodedMulti = decode(multiSegment);
  assert.strictEqual(decodedMulti.length, 2);
  assert.deepStrictEqual(decodedMulti[0], [[0, 0, 0, 0], [9, 0, 0, 9]]);
  assert.deepStrictEqual(decodedMulti[1], [[8, 0, 0, 0]]);
  assert.strictEqual(encode(decodedMulti), multiSegment);

  // 6. encode serializes nested coordinate segment arrays into VLQ encoded sourcemap mapping strings
  const customSegments = [
    [[0, 0, 0, 0], [4, 0, 0, 4]],
    [[0, 0, 1, 0]]
  ];
  const encodedCustom = encode(customSegments);
  assert.strictEqual(typeof encodedCustom, 'string');
  assert.deepStrictEqual(decode(encodedCustom), customSegments);

  // 7. encode and decode perform lossless roundtrips on complex multi-line sourcemap mappings
  const complexMappings = 'AAAA,SAAS,aAAa;QAAT,SAAS;aAAa';
  const roundtripped = encode(decode(complexMappings));
  assert.strictEqual(roundtripped, complexMappings);

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

runContract();