type-is 2.1.0

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/type-is@2.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/type-is@2.1.0
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:sha256:56ce3f4263ae0a5032f1658b2a432bb3bae2d02a63850a9044feff3830cf05a3","constraints":{"executionContext":"node"},"contract":["typeis(req, types) matches the Content-Type header of a request against candidate types and returns the matching type","typeis(req, types) returns null when the request has no body headers (neither content-length nor transfer-encoding)","typeis(req, types) returns false when the request body content-type does not match candidate types","typeis.hasBody(req) returns true when request has content-length or transfer-encoding headers","typeis.is(mediaType, types) matches media type strings against extensions, types, or wildcards","typeis.normalize(type) normalizes type extensions and shorthand names to full MIME types"],"goal":"verify pkg:npm/type-is@2.1.0","kind":"HOW","packages":["pkg:npm/type-is@2.1.0"],"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/type-is@2.1.0"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

{
  "name": "type-is-sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "type-is-sample",
      "version": "1.0.0",
      "dependencies": {
        "type-is": "2.1.0"
      }
    },
    "node_modules/content-type": {
      "version": "2.1.0",
      "resolved": "https://registry.npmjs.org/content-type/-/content-type-2.1.0.tgz",
      "integrity": "sha512-mj7UPXE0jaqaOsukNZRUEfEi2AcL7C/vwmwcHV0O97eO1E1pxBZuyjlZrx5seTaNBg1U6+o35wpa35Qfcc+7ag==",
      "license": "MIT",
      "engines": {
        "node": ">=18"
      },
      "funding": {
        "type": "opencollective",
        "url": "https://opencollective.com/express"
      }
    },
    "node_modules/media-typer": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/media-typer/-/media-typer-1.1.1.tgz",
      "integrity": "sha512-yz3xRaG20c6/BOzvYoDaGtPmGscs7YivItZEEqe6GbwNfHuxu9YNmvnEkMzKldAGY4/80pRcQRZSEnhquk9XuQ==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.8"
      },
      "funding": {
        "type": "opencollective",
        "url": "https://opencollective.com/express"
      }
    },
    "node_modules/mime-db": {
      "version": "1.54.0",
      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.54.0.tgz",
      "integrity": "sha512-aU5EJuIN2WDemCcAp2vFBfp/m4EAhWJnUNSSw0ixs7/kXbd6Pg64EmwJkNdFhB8aWt1sH2CTXrLxo/iAGV3oPQ==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.6"
      }
    },
    "node_modules/mime-types": {
      "version": "3.0.2",
      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-3.0.2.tgz",
      "integrity": "sha512-Lbgzdk0h4juoQ9fCKXW4by0UJqj+nOOrI9MJ1sSj4nI8aI2eo1qmvQEie4VD1glsS250n15LsWsYtCugiStS5A==",
      "license": "MIT",
      "dependencies": {
        "mime-db": "^1.54.0"
      },
      "engines": {
        "node": ">=18"
      },
      "funding": {
        "type": "opencollective",
        "url": "https://opencollective.com/express"
      }
    },
    "node_modules/type-is": {
      "version": "2.1.0",
      "resolved": "https://registry.npmjs.org/type-is/-/type-is-2.1.0.tgz",
      "integrity": "sha512-faYHw0anBbc/kWF3zFTEnxSFOAGUX9GFbOBthvDdLsIlEoWOFOtS0zgCiQYwIskL9iGXZL3kAXD8OoZ4GmMATA==",
      "license": "MIT",
      "dependencies": {
        "content-type": "^2.0.0",
        "media-typer": "^1.1.0",
        "mime-types": "^3.0.0"
      },
      "engines": {
        "node": ">= 18"
      },
      "funding": {
        "type": "opencollective",
        "url": "https://opencollective.com/express"
      }
    }
  }
}

{
  "name": "type-is-sample",
  "version": "1.0.0",
  "description": "Minimal sample verifying type-is",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.cjs"
  },
  "dependencies": {
    "type-is": "2.1.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/type-is@2.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/type-is@2.1.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

'use strict';

const typeis = require('type-is');

/**
 * Checks if the incoming request has a body and matches any of the candidate types.
 *
 * @param {object} req - HTTP request object with headers.
 * @param {string|string[]} candidateTypes - Acceptable MIME types, shorthands, or wildcards.
 * @returns {string|false|null} - Matching type string, false if mismatch, or null if no body.
 */
function checkRequestType(req, candidateTypes) {
  const types = Array.isArray(candidateTypes) ? candidateTypes : [candidateTypes];
  return typeis(req, types);
}

/**
 * Checks whether an HTTP request contains a request body.
 *
 * @param {object} req - HTTP request object with headers.
 * @returns {boolean} - True if body is present, false otherwise.
 */
function hasRequestBody(req) {
  return typeis.hasBody(req);
}

/**
 * Compares a media type string against candidate types.
 *
 * @param {string} mediaType - Media type string (e.g. 'application/json').
 * @param {string|string[]} candidateTypes - Candidate types, shorthands, or wildcards.
 * @returns {string|false} - Matching type string or false.
 */
function matchMediaType(mediaType, candidateTypes) {
  const types = Array.isArray(candidateTypes) ? candidateTypes : [candidateTypes];
  return typeis.is(mediaType, types);
}

/**
 * Normalizes a type shorthand or extension into a full MIME type.
 *
 * @param {string} type - Extension or shorthand (e.g. 'json', '+json', 'html').
 * @returns {string|false} - Normalized MIME pattern or false.
 */
function normalizeType(type) {
  return typeis.normalize(type);
}

module.exports = {
  typeis,
  checkRequestType,
  hasRequestBody,
  matchMediaType,
  normalizeType,
};

const assert = require('node:assert/strict');
const typeis = require('type-is');
const {
  checkRequestType,
  hasRequestBody,
  matchMediaType,
  normalizeType,
} = require('../src/index.js');

function createMockReq(headers = {}) {
  return {
    headers: { ...headers },
  };
}

async function main() {
  // Contract 1: typeis(req, types) matches the Content-Type header of a request against candidate types and returns the matching type
  {
    const reqJson = createMockReq({
      'content-type': 'application/json; charset=utf-8',
      'content-length': '42',
    });
    assert.strictEqual(typeis(reqJson, ['json', 'html']), 'json');
    assert.strictEqual(typeis(reqJson, ['application/json']), 'application/json');
    assert.strictEqual(checkRequestType(reqJson, ['json', 'html']), 'json');

    const reqHtml = createMockReq({
      'content-type': 'text/html; charset=utf-8',
      'transfer-encoding': 'chunked',
    });
    assert.strictEqual(typeis(reqHtml, ['html', 'json']), 'html');
    assert.strictEqual(checkRequestType(reqHtml, 'html'), 'html');

    const reqCustom = createMockReq({
      'content-type': 'application/vnd.api+json',
      'content-length': '100',
    });
    assert.strictEqual(typeis(reqCustom, ['+json']), 'application/vnd.api+json');
    assert.strictEqual(checkRequestType(reqCustom, ['+json']), 'application/vnd.api+json');
  }

  // Contract 2: typeis(req, types) returns null when the request has no body headers (neither content-length nor transfer-encoding)
  {
    const reqNoBody = createMockReq({
      'content-type': 'application/json',
    });
    assert.strictEqual(typeis(reqNoBody, ['json']), null);
    assert.strictEqual(checkRequestType(reqNoBody, ['json']), null);

    const reqEmptyHeaders = createMockReq({});
    assert.strictEqual(typeis(reqEmptyHeaders, ['json', 'html']), null);
    assert.strictEqual(checkRequestType(reqEmptyHeaders, ['json', 'html']), null);
  }

  // Contract 3: typeis(req, types) returns false when the request body content-type does not match candidate types
  {
    const reqText = createMockReq({
      'content-type': 'text/plain',
      'content-length': '20',
    });
    assert.strictEqual(typeis(reqText, ['json', 'html']), false);
    assert.strictEqual(checkRequestType(reqText, ['json', 'html']), false);

    const reqPng = createMockReq({
      'content-type': 'image/png',
      'transfer-encoding': 'chunked',
    });
    assert.strictEqual(typeis(reqPng, ['application/json', 'text/*']), false);
    assert.strictEqual(checkRequestType(reqPng, ['application/json', 'text/*']), false);
  }

  // Contract 4: typeis.hasBody(req) returns true when request has content-length or transfer-encoding headers
  {
    const reqLength = createMockReq({ 'content-length': '15' });
    assert.strictEqual(typeis.hasBody(reqLength), true);
    assert.strictEqual(hasRequestBody(reqLength), true);

    const reqChunked = createMockReq({ 'transfer-encoding': 'chunked' });
    assert.strictEqual(typeis.hasBody(reqChunked), true);
    assert.strictEqual(hasRequestBody(reqChunked), true);

    const reqEmpty = createMockReq({});
    assert.strictEqual(typeis.hasBody(reqEmpty), false);
    assert.strictEqual(hasRequestBody(reqEmpty), false);
  }

  // Contract 5: typeis.is(mediaType, types) matches media type strings against extensions, types, or wildcards
  {
    assert.strictEqual(typeis.is('application/json', ['json']), 'json');
    assert.strictEqual(typeis.is('application/json', ['text/html', 'application/json']), 'application/json');
    assert.strictEqual(typeis.is('image/png', ['image/*']), 'image/png');
    assert.strictEqual(typeis.is('text/html', ['json', 'image/*']), false);

    assert.strictEqual(matchMediaType('application/json', ['json']), 'json');
    assert.strictEqual(matchMediaType('image/png', ['image/*']), 'image/png');
    assert.strictEqual(matchMediaType('text/html', ['json']), false);
  }

  // Contract 6: typeis.normalize(type) normalizes type extensions and shorthand names to full MIME types
  {
    assert.strictEqual(typeis.normalize('json'), 'application/json');
    assert.strictEqual(typeis.normalize('html'), 'text/html');
    assert.strictEqual(typeis.normalize('+json'), '*/*+json');
    assert.strictEqual(typeis.normalize('application/json'), 'application/json');

    assert.strictEqual(normalizeType('json'), 'application/json');
    assert.strictEqual(normalizeType('html'), 'text/html');
    assert.strictEqual(normalizeType('+json'), '*/*+json');
  }

  console.log('All contracts verified successfully.');
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});