type-check 0.4.0: typeCheck

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-check.typeCheck in pkg:npm/type-check@0.4.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/type-check@0.4.0
Demonstrate these symbols/APIs:
  - type-check.typeCheck

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:sha256:21dc7eb599ffb1bef9a6e16d8ad34c55fa0efe350b9c3cf12e0ba1d14cb5c610","contract":["assert typeCheck validates primitive types (Number, String, Boolean, Undefined, Null, Array, Object, RegExp)","assert typeCheck rejects mismatched primitive types","assert typeCheck validates union types and wildcard expressions","assert typeCheck validates array and tuple structures","assert typeCheck validates closed object records, optional fields with Maybe, and open records with ...","assert typeCheck supports custom type specifications via customTypes option"],"goal":"verify type-check.typeCheck in pkg:npm/type-check@0.4.0","kind":"HOW","packages":["pkg:npm/type-check@0.4.0"],"schemaVersion":1,"symbols":["type-check.typeCheck"]},"contractCommand":["node","test/contract.js"],"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-check@0.4.0"],"schemaVersion":1,"subject":"pkg:npm/type-check@0.4.0","symbols":["type-check.typeCheck"],"verifierAdapter":"node-typescript@1"}

const { typeCheck } = require('type-check');

module.exports = {
  typeCheck,
};

{
  "name": "sample-2765681028",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-2765681028",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "type-check": "0.4.0"
      }
    },
    "node_modules/prelude-ls": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",
      "integrity": "sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.8.0"
      }
    },
    "node_modules/type-check": {
      "version": "0.4.0",
      "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.4.0.tgz",
      "integrity": "sha512-XleUoc9uwGXqjWwXaUTZAmzMcFZ5858QA2vvx1Ur5xIcixXIP+8LnFDgRplU30us6teqdlskFfu+ae4K79Ooew==",
      "license": "MIT",
      "dependencies": {
        "prelude-ls": "^1.2.1"
      },
      "engines": {
        "node": ">= 0.8.0"
      }
    }
  }
}

{
  "name": "sample-2765681028",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "license": "MIT-0",
  "dependencies": {
    "type-check": "0.4.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify type-check.typeCheck in pkg:npm/type-check@0.4.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/type-check@0.4.0"
  ],
  "symbols": [
    "type-check.typeCheck"
  ]
}

const assert = require('node:assert');
const { typeCheck } = require('type-check');

// 1. Primitive types validation
assert.strictEqual(typeCheck('Number', 42), true, 'Number should match integer 42');
assert.strictEqual(typeCheck('Number', 3.14), true, 'Number should match float 3.14');
assert.strictEqual(typeCheck('String', 'hello'), true, 'String should match string');
assert.strictEqual(typeCheck('Boolean', true), true, 'Boolean should match true');
assert.strictEqual(typeCheck('Boolean', false), true, 'Boolean should match false');
assert.strictEqual(typeCheck('Undefined', undefined), true, 'Undefined should match undefined');
assert.strictEqual(typeCheck('Null', null), true, 'Null should match null');
assert.strictEqual(typeCheck('Array', [1, 2, 3]), true, 'Array should match array');
assert.strictEqual(typeCheck('Object', { key: 'val' }), true, 'Object should match object');
assert.strictEqual(typeCheck('RegExp', /abc/), true, 'RegExp should match regular expression');

// 2. Mismatched primitive types rejection
assert.strictEqual(typeCheck('Number', '42'), false, 'Number should reject string "42"');
assert.strictEqual(typeCheck('String', 123), false, 'String should reject number 123');
assert.strictEqual(typeCheck('Boolean', 'true'), false, 'Boolean should reject string "true"');
assert.strictEqual(typeCheck('Undefined', null), false, 'Undefined should reject null');
assert.strictEqual(typeCheck('Null', undefined), false, 'Null should reject undefined');

// 3. Union types and wildcard expressions
assert.strictEqual(typeCheck('Number | String', 10), true, 'Union should match Number');
assert.strictEqual(typeCheck('Number | String', 'sample'), true, 'Union should match String');
assert.strictEqual(typeCheck('Number | String', false), false, 'Union should reject Boolean');
assert.strictEqual(typeCheck('count::Number', 5), true, 'Comment syntax should be ignored and pass validation');
assert.strictEqual(typeCheck('*', { any: 'value' }), true, 'Wildcard should match object');
assert.strictEqual(typeCheck('*', 123), true, 'Wildcard should match primitive');

// 4. Array and tuple structures
assert.strictEqual(typeCheck('[Number]', [1, 2, 3]), true, 'Homogeneous array [Number] should pass');
assert.strictEqual(typeCheck('[Number]', [1, '2', 3]), false, 'Homogeneous array [Number] should fail with mixed types');
assert.strictEqual(typeCheck('(String, Number)', ['alice', 30]), true, 'Tuple (String, Number) should match 2 elements');
assert.strictEqual(typeCheck('(String, Number)', ['alice']), false, 'Tuple should fail on missing elements');
assert.strictEqual(typeCheck('(String, Number)', ['alice', 30, true]), false, 'Tuple should fail on extra elements');

// 5. Closed object records, optional fields with Maybe, and open records with ...
assert.strictEqual(typeCheck('{name: String, age: Number}', { name: 'Alice', age: 30 }), true, 'Exact object fields should match');
assert.strictEqual(typeCheck('{name: String, age: Number}', { name: 'Alice' }), false, 'Missing non-maybe field should fail');
assert.strictEqual(typeCheck('{name: String, age: Maybe Number}', { name: 'Alice' }), true, 'Missing maybe field should pass');
assert.strictEqual(typeCheck('{name: String, age: Maybe Number}', { name: 'Alice', age: null }), true, 'Null maybe field should pass');
assert.strictEqual(typeCheck('{name: String}', { name: 'Alice', extra: 99 }), false, 'Closed object should reject extraneous fields');
assert.strictEqual(typeCheck('{name: String, ...}', { name: 'Alice', extra: 99 }), true, 'Open record (...) should accept extraneous fields');

// 6. Custom type specifications via customTypes option
const options = {
  customTypes: {
    Even: {
      typeOf: 'Number',
      validate: (x) => x % 2 === 0,
    },
  },
};
assert.strictEqual(typeCheck('Even', 4, options), true, 'Custom type Even matches 4');
assert.strictEqual(typeCheck('Even', 5, options), false, 'Custom type Even rejects 5');
assert.strictEqual(typeCheck('Even', '4', options), false, 'Custom type Even rejects non-Number');

console.log('Contract assertions passed.');