@jridgewell/gen-mapping 0.3.13: addMapping

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 @jridgewell/gen-mapping.addMapping in pkg:npm/%40jridgewell/gen-mapping@0.3.13
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40jridgewell/gen-mapping@0.3.13
Demonstrate these symbols/APIs:
  - @jridgewell/gen-mapping.addMapping
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:sha256:2bf81508d0896a51bab08398c45547c817b0154ab24d6c0c246f5c1396370541","constraints":{"executionContext":"node"},"contract":["addMapping associates generated 1-based line and 0-based column with original positions","addMapping creates sourceless 1-field segments when source is omitted","addMapping associates identifier names creating 5-field segments and registers symbol names","addMapping optionally populates inline source content for mapped source files","addMapping maintains column sort order when inserting mappings out of order on the same line","addMapping supports multi-line generated positions producing segmented decoded mappings"],"goal":"verify @jridgewell/gen-mapping.addMapping in pkg:npm/%40jridgewell/gen-mapping@0.3.13","kind":"HOW","packages":["pkg:npm/%40jridgewell/gen-mapping@0.3.13"],"schemaVersion":1,"symbols":["@jridgewell/gen-mapping.addMapping"]},"contractCommand":["node","test/contract.mjs"],"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/gen-mapping@0.3.13"],"schemaVersion":1,"subject":"pkg:npm/%40jridgewell/gen-mapping@0.3.13","symbols":["@jridgewell/gen-mapping.addMapping"],"verifierAdapter":"node-typescript@1"}

{
  "name": "gen-mapping-sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "gen-mapping-sample",
      "version": "1.0.0",
      "dependencies": {
        "@jridgewell/gen-mapping": "0.3.13"
      }
    },
    "node_modules/@jridgewell/gen-mapping": {
      "version": "0.3.13",
      "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.13.tgz",
      "integrity": "sha512-2kkt/7niJ6MgEPxF0bYdQ6etZaA+fQvDcLKckhy1yIQOzaoKjBBjSj63/aLVjYE3qhRt5dvM+uUyfCg6UKCBbA==",
      "license": "MIT",
      "dependencies": {
        "@jridgewell/sourcemap-codec": "^1.5.0",
        "@jridgewell/trace-mapping": "^0.3.24"
      }
    },
    "node_modules/@jridgewell/resolve-uri": {
      "version": "3.1.2",
      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.2.tgz",
      "integrity": "sha512-bRISgCIjP20/tbWSPWMEi54QVPRZExkuD9lJL+UIxUKtwVJA8wW1Trb1jMs1RFXo1CBTNZ/5hpC9QvmKWdopKw==",
      "license": "MIT",
      "engines": {
        "node": ">=6.0.0"
      }
    },
    "node_modules/@jridgewell/sourcemap-codec": {
      "version": "1.6.0",
      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.6.0.tgz",
      "integrity": "sha512-T7jf+5zgsZHwNJ4lvQ7/aezbyk0nNX+zJVWpmHA7VYsEx7a7qr5Rg5IbtJFqkgze5Y2sruq1RUY8Q837Od7iFw==",
      "license": "MIT"
    },
    "node_modules/@jridgewell/trace-mapping": {
      "version": "0.3.31",
      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.31.tgz",
      "integrity": "sha512-zzNR+SdQSDJzc8joaeP8QQoCQr8NuYx2dIIytl1QeBEZHJ9uW6hebsrYgbz8hJwUQao3TWCMtmfV8Nu1twOLAw==",
      "license": "MIT",
      "dependencies": {
        "@jridgewell/resolve-uri": "^3.1.0",
        "@jridgewell/sourcemap-codec": "^1.4.14"
      }
    }
  }
}

{
  "name": "gen-mapping-sample",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification for @jridgewell/gen-mapping",
  "dependencies": {
    "@jridgewell/gen-mapping": "0.3.13"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @jridgewell/gen-mapping.addMapping in pkg:npm/%40jridgewell/gen-mapping@0.3.13",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40jridgewell/gen-mapping@0.3.13"
  ],
  "symbols": [
    "@jridgewell/gen-mapping.addMapping"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert';
import {
  GenMapping,
  addMapping,
  toDecodedMap,
  toEncodedMap,
  allMappings,
} from '@jridgewell/gen-mapping';

// 1. addMapping associates generated 1-based line and 0-based column with original positions
{
  const map = new GenMapping();
  addMapping(map, {
    generated: { line: 1, column: 0 },
    source: 'foo.js',
    original: { line: 1, column: 0 },
  });
  const decoded = toDecodedMap(map);
  assert.deepStrictEqual(decoded.sources, ['foo.js']);
  // Line index 0 in decoded.mappings corresponds to generated line 1.
  // Segment: [genColumn, sourceIndex, originalLine (0-based), originalColumn (0-based)]
  assert.deepStrictEqual(decoded.mappings[0], [[0, 0, 0, 0]]);
  const mappings = allMappings(map);
  assert.strictEqual(mappings.length, 1);
  assert.deepStrictEqual(mappings[0], {
    generated: { line: 1, column: 0 },
    source: 'foo.js',
    original: { line: 1, column: 0 },
    name: undefined,
  });
}

// 2. addMapping creates sourceless 1-field segments when source is omitted
{
  const map = new GenMapping();
  addMapping(map, {
    generated: { line: 1, column: 4 },
  });
  const decoded = toDecodedMap(map);
  // Sourceless segment only contains generated column: [4]
  assert.deepStrictEqual(decoded.mappings[0], [[4]]);
  const mappings = allMappings(map);
  assert.strictEqual(mappings.length, 1);
  assert.deepStrictEqual(mappings[0], {
    generated: { line: 1, column: 4 },
    source: undefined,
    original: undefined,
    name: undefined,
  });
}

// 3. addMapping associates identifier names creating 5-field segments and registers symbol names
{
  const map = new GenMapping();
  addMapping(map, {
    generated: { line: 1, column: 10 },
    source: 'bar.js',
    original: { line: 5, column: 2 },
    name: 'calculateTotal',
  });
  const decoded = toDecodedMap(map);
  assert.deepStrictEqual(decoded.names, ['calculateTotal']);
  // Segment: [genCol, sourceIdx, origLine(0-based=4), origCol(0-based=2), nameIdx(0)]
  assert.deepStrictEqual(decoded.mappings[0], [[10, 0, 4, 2, 0]]);
  const mappings = allMappings(map);
  assert.strictEqual(mappings.length, 1);
  assert.deepStrictEqual(mappings[0], {
    generated: { line: 1, column: 10 },
    source: 'bar.js',
    original: { line: 5, column: 2 },
    name: 'calculateTotal',
  });
}

// 4. addMapping optionally populates inline source content for mapped source files
{
  const map = new GenMapping();
  const sourceCode = 'const x = 42;';
  addMapping(map, {
    generated: { line: 1, column: 0 },
    source: 'inline.js',
    original: { line: 1, column: 0 },
    content: sourceCode,
  });
  const decoded = toDecodedMap(map);
  assert.deepStrictEqual(decoded.sources, ['inline.js']);
  assert.deepStrictEqual(decoded.sourcesContent, [sourceCode]);
}

// 5. addMapping maintains column sort order when inserting mappings out of order on the same line
{
  const map = new GenMapping();
  // Insert column 20 first, then column 5
  addMapping(map, {
    generated: { line: 1, column: 20 },
    source: 'order.js',
    original: { line: 1, column: 20 },
  });
  addMapping(map, {
    generated: { line: 1, column: 5 },
    source: 'order.js',
    original: { line: 1, column: 5 },
  });
  const decoded = toDecodedMap(map);
  // Column 5 should be sorted before column 20
  assert.strictEqual(decoded.mappings[0].length, 2);
  assert.strictEqual(decoded.mappings[0][0][0], 5);
  assert.strictEqual(decoded.mappings[0][1][0], 20);
}

// 6. addMapping supports multi-line generated positions producing segmented decoded mappings
{
  const map = new GenMapping({ file: 'output.js' });
  addMapping(map, {
    generated: { line: 1, column: 0 },
    source: 'src.js',
    original: { line: 10, column: 0 },
  });
  addMapping(map, {
    generated: { line: 2, column: 4 },
    source: 'src.js',
    original: { line: 20, column: 2 },
  });
  const decoded = toDecodedMap(map);
  assert.strictEqual(decoded.mappings.length, 2);
  assert.deepStrictEqual(decoded.mappings[0], [[0, 0, 9, 0]]);
  assert.deepStrictEqual(decoded.mappings[1], [[4, 0, 19, 2]]);

  const encoded = toEncodedMap(map);
  assert.strictEqual(encoded.version, 3);
  assert.strictEqual(encoded.file, 'output.js');
  assert.strictEqual(typeof encoded.mappings, 'string');
}

console.log('Contract passed');