type-fest 0.13.1: types

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 type-fest.types in pkg:npm/type-fest@0.13.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/type-fest@0.13.1
Demonstrate these symbols/APIs:
  - type-fest.types

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:sha256:0e8a4248909d66152ff3e023dfc98c90dce24dbb08a66e1ca3e700643e552372","contract":["type-fest package manifest declares types field pointing to entry declaration file index.d.ts","type-fest entry declaration index.d.ts exports basic types and utility types","type-fest basic declarations define Primitive union covering standard JavaScript primitives","type-fest tsconfig declarations export TsConfigJson interface with optional compilerOptions","type-fest literal-union declaration exports LiteralUnion type combining LiteralType with guarded Primitive"],"goal":"verify type-fest.types in pkg:npm/type-fest@0.13.1","kind":"HOW","packages":["pkg:npm/type-fest@0.13.1"],"schemaVersion":1,"symbols":["type-fest.types"]},"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/type-fest@0.13.1"],"schemaVersion":1,"subject":"pkg:npm/type-fest@0.13.1","symbols":["type-fest.types"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-type-fest-types",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-type-fest-types",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "type-fest": "0.13.1"
      }
    },
    "node_modules/type-fest": {
      "version": "0.13.1",
      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",
      "integrity": "sha512-34R7HTnG0XIJcBSn5XhDd7nNFPRcXYRZrBB2O2jdKqYODldSzBAqzsWoZYYvduky73toYS/ESqxPvkDf/F0XMg==",
      "license": "(MIT OR CC0-1.0)",
      "engines": {
        "node": ">=10"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    }
  }
}

{
  "name": "sample-type-fest-types",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "dependencies": {
    "type-fest": "0.13.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify type-fest.types in pkg:npm/type-fest@0.13.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/type-fest@0.13.1"
  ],
  "symbols": [
    "type-fest.types"
  ]
}

import assert from 'node:assert/strict';
import fs from 'node:fs';
import path from 'node:path';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);

// Contract 1: type-fest package manifest declares types field pointing to entry declaration file index.d.ts
{
  const pkgJson = require('type-fest/package.json');
  assert.equal(pkgJson.name, 'type-fest');
  assert.equal(pkgJson.version, '0.13.1');
  assert.equal(pkgJson.types, 'index.d.ts');
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const typesPath = path.join(pkgDir, pkgJson.types);
  assert.ok(fs.existsSync(typesPath), 'types entry file index.d.ts must exist');
}

// Contract 2: type-fest entry declaration index.d.ts exports basic types and utility types
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const indexDtsPath = path.join(pkgDir, 'index.d.ts');
  const indexDtsContent = fs.readFileSync(indexDtsPath, 'utf8');
  assert.ok(
    indexDtsContent.includes("export * from './source/basic';"),
    'index.d.ts must re-export basic types'
  );
  assert.ok(
    indexDtsContent.includes("export {LiteralUnion} from './source/literal-union';"),
    'index.d.ts must export LiteralUnion'
  );
  assert.ok(
    indexDtsContent.includes("export {TsConfigJson} from './source/tsconfig-json';"),
    'index.d.ts must export TsConfigJson'
  );
}

// Contract 3: type-fest basic declarations define Primitive union covering standard JavaScript primitives
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const basicDtsPath = path.join(pkgDir, 'source', 'basic.d.ts');
  assert.ok(fs.existsSync(basicDtsPath), 'source/basic.d.ts must exist');
  const basicDtsContent = fs.readFileSync(basicDtsPath, 'utf8');
  assert.ok(
    basicDtsContent.includes('export type Primitive ='),
    'source/basic.d.ts must declare Primitive type'
  );
  assert.ok(basicDtsContent.includes('null'), 'Primitive must include null');
  assert.ok(basicDtsContent.includes('undefined'), 'Primitive must include undefined');
  assert.ok(basicDtsContent.includes('string'), 'Primitive must include string');
  assert.ok(basicDtsContent.includes('number'), 'Primitive must include number');
  assert.ok(basicDtsContent.includes('boolean'), 'Primitive must include boolean');
  assert.ok(basicDtsContent.includes('symbol'), 'Primitive must include symbol');
  assert.ok(basicDtsContent.includes('bigint'), 'Primitive must include bigint');
}

// Contract 4: type-fest tsconfig declarations export TsConfigJson interface with optional compilerOptions
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const tsconfigDtsPath = path.join(pkgDir, 'source', 'tsconfig-json.d.ts');
  assert.ok(fs.existsSync(tsconfigDtsPath), 'source/tsconfig-json.d.ts must exist');
  const tsconfigDtsContent = fs.readFileSync(tsconfigDtsPath, 'utf8');
  assert.ok(
    tsconfigDtsContent.includes('declare namespace TsConfigJson {'),
    'TsConfigJson namespace must be declared'
  );
  assert.ok(
    tsconfigDtsContent.includes('export interface TsConfigJson {'),
    'TsConfigJson interface must be exported'
  );
  assert.ok(
    tsconfigDtsContent.includes('compilerOptions?: TsConfigJson.CompilerOptions;'),
    'TsConfigJson must declare optional compilerOptions'
  );
}

// Contract 5: type-fest literal-union declaration exports LiteralUnion type combining LiteralType with guarded Primitive
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const literalUnionDtsPath = path.join(pkgDir, 'source', 'literal-union.d.ts');
  assert.ok(fs.existsSync(literalUnionDtsPath), 'source/literal-union.d.ts must exist');
  const literalUnionDtsContent = fs.readFileSync(literalUnionDtsPath, 'utf8');
  assert.ok(
    literalUnionDtsContent.includes('export type LiteralUnion<'),
    'LiteralUnion type must be declared'
  );
  assert.ok(
    literalUnionDtsContent.includes('LiteralType extends BaseType,'),
    'LiteralUnion must constrain LiteralType'
  );
  assert.ok(
    literalUnionDtsContent.includes('BaseType extends Primitive'),
    'LiteralUnion must constrain BaseType to Primitive'
  );
  assert.ok(
    literalUnionDtsContent.includes('LiteralType | (BaseType & {_?: never})'),
    'LiteralUnion must preserve auto-completion via guarded primitive intersection'
  );
}

console.log('All pkg:npm/type-fest@0.13.1 type-fest.types contracts passed successfully.');