type-fest 0.21.3: Except, PackageJson, SetOptional

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 Except and SetOptional in pkg:npm/type-fest@0.21.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/type-fest@0.21.3
Demonstrate these symbols/APIs:
  - Except
  - PackageJson
  - SetOptional

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:sha256:37c5d86f4880a0b4087f73177a6020316f05ce3daa1bec302ea702c9f1355695","contract":["type-fest package.json defines package name as type-fest and version as 0.21.3 with types entry point","type-fest base declarations export Except, SetOptional, and PackageJson symbols","Except type definition is declared as strict Pick-Exclude utility restricting omitted keys to target object keys","SetOptional type definition combines Except and Partial-Pick to make specified keys optional","PackageJson type definition exports structured declarations including Scripts, DirectoryLocations, and Person"],"goal":"verify Except and SetOptional in pkg:npm/type-fest@0.21.3","kind":"HOW","packages":["pkg:npm/type-fest@0.21.3"],"schemaVersion":1,"symbols":["Except","PackageJson","SetOptional"]},"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/type-fest@0.21.3"],"schemaVersion":1,"subject":"pkg:npm/type-fest@0.21.3","symbols":["Except","PackageJson","SetOptional"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-type-fest-except-set-optional",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-type-fest-except-set-optional",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "type-fest": "0.21.3"
      }
    },
    "node_modules/type-fest": {
      "version": "0.21.3",
      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.21.3.tgz",
      "integrity": "sha512-t0rzBq87m3fVcduHDUFhKmyyX+9eo6WQjZvf51Ea/M0Q7+T374Jp1aUiyUl0GKxp8M/OETVHSDvmkyPgvX+X2w==",
      "license": "(MIT OR CC0-1.0)",
      "engines": {
        "node": ">=10"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    }
  }
}

{
  "name": "sample-type-fest-except-set-optional",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "dependencies": {
    "type-fest": "0.21.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify Except and SetOptional in pkg:npm/type-fest@0.21.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/type-fest@0.21.3"
  ],
  "symbols": [
    "Except",
    "PackageJson",
    "SetOptional"
  ]
}

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.json defines package name as type-fest and version as 0.21.3 with types entry point
{
  const pkgJson = require('type-fest/package.json');
  assert.equal(pkgJson.name, 'type-fest');
  assert.equal(pkgJson.version, '0.21.3');
  assert.equal(pkgJson.types, './index.d.ts');
}

// Contract 2: type-fest base declarations export Except, SetOptional, and PackageJson symbols
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const baseDtsPath = path.join(pkgDir, 'base.d.ts');
  assert.ok(fs.existsSync(baseDtsPath), 'base.d.ts must exist');
  const baseDtsContent = fs.readFileSync(baseDtsPath, 'utf8');
  assert.ok(baseDtsContent.includes("export {Except} from './source/except';"), 'Except must be exported from base.d.ts');
  assert.ok(baseDtsContent.includes("export {SetOptional} from './source/set-optional';"), 'SetOptional must be exported from base.d.ts');
  assert.ok(baseDtsContent.includes("export {PackageJson} from './source/package-json';"), 'PackageJson must be exported from base.d.ts');
}

// Contract 3: Except type definition is declared as strict Pick-Exclude utility restricting omitted keys to target object keys
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const exceptDtsPath = path.join(pkgDir, 'source', 'except.d.ts');
  assert.ok(fs.existsSync(exceptDtsPath), 'source/except.d.ts must exist');
  const exceptDtsContent = fs.readFileSync(exceptDtsPath, 'utf8');
  assert.ok(
    exceptDtsContent.includes('export type Except<ObjectType, KeysType extends keyof ObjectType>'),
    'Except must constrain KeysType extends keyof ObjectType'
  );
  assert.ok(
    exceptDtsContent.includes('Pick<ObjectType, Exclude<keyof ObjectType, KeysType>>'),
    'Except must define Pick with Exclude'
  );
}

// Contract 4: SetOptional type definition combines Except and Partial-Pick to make specified keys optional
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const setOptionalDtsPath = path.join(pkgDir, 'source', 'set-optional.d.ts');
  assert.ok(fs.existsSync(setOptionalDtsPath), 'source/set-optional.d.ts must exist');
  const setOptionalDtsContent = fs.readFileSync(setOptionalDtsPath, 'utf8');
  assert.ok(
    setOptionalDtsContent.includes('export type SetOptional<BaseType, Keys extends keyof BaseType>'),
    'SetOptional must constrain Keys extends keyof BaseType'
  );
  assert.ok(
    setOptionalDtsContent.includes('Except<BaseType, Keys>'),
    'SetOptional must use Except for remaining keys'
  );
  assert.ok(
    setOptionalDtsContent.includes('Partial<Pick<BaseType, Keys>>'),
    'SetOptional must use Partial<Pick> for optional keys'
  );
}

// Contract 5: PackageJson type definition exports structured declarations including Scripts, DirectoryLocations, and Person
{
  const pkgDir = path.dirname(require.resolve('type-fest/package.json'));
  const packageJsonDtsPath = path.join(pkgDir, 'source', 'package-json.d.ts');
  assert.ok(fs.existsSync(packageJsonDtsPath), 'source/package-json.d.ts must exist');
  const packageJsonDtsContent = fs.readFileSync(packageJsonDtsPath, 'utf8');
  assert.ok(packageJsonDtsContent.includes('declare namespace PackageJson'), 'PackageJson must declare namespace');
  assert.ok(packageJsonDtsContent.includes('export type Person ='), 'PackageJson must declare Person type');
  assert.ok(packageJsonDtsContent.includes('export interface DirectoryLocations'), 'PackageJson must declare DirectoryLocations');
  assert.ok(packageJsonDtsContent.includes('export type Scripts ='), 'PackageJson must declare Scripts type');
  assert.ok(packageJsonDtsContent.includes('type PackageJson ='), 'PackageJson type must be declared');
}

console.log('All pkg:npm/type-fest@0.21.3 contracts passed successfully.');