eventsource 3.0.7: ErrorEvent

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 eventsource.ErrorEvent in pkg:npm/eventsource@3.0.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/eventsource@3.0.7
Demonstrate these symbols/APIs:
  - eventsource.ErrorEvent

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:sha256:0bd3c5da7b877f0de637d0f7fe7b260f3b9307854c3dddfdd26737230d0df88f","contract":["ErrorEvent extends Event and initializes type, message, and code properties from constructor options","ErrorEvent defaults code and message to undefined when initialized without options","ErrorEvent custom inspection formats properties including type, message, and code","EventSource dispatches ErrorEvent instance to onerror callback with HTTP error code on HTTP failure","EventSource dispatches ErrorEvent via addEventListener on connection failure"],"goal":"verify eventsource.ErrorEvent in pkg:npm/eventsource@3.0.7","kind":"HOW","packages":["pkg:npm/eventsource@3.0.7"],"schemaVersion":1,"symbols":["eventsource.ErrorEvent"]},"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/eventsource@3.0.7"],"schemaVersion":1,"subject":"pkg:npm/eventsource@3.0.7","symbols":["eventsource.ErrorEvent"],"verifierAdapter":"node-typescript@1"}

import { EventSource, ErrorEvent } from 'eventsource';

/**
 * Creates an ErrorEvent instance with given type and error details.
 *
 * @param {string} type - Event type name (e.g. 'error').
 * @param {{ message?: string, code?: number }} [initDict] - Optional error attributes.
 * @returns {ErrorEvent}
 */
export function createErrorEvent(type = 'error', initDict) {
  return new ErrorEvent(type, initDict);
}

/**
 * Creates an EventSource instance configured for the specified SSE endpoint.
 *
 * @param {string | URL} url - Target URL.
 * @param {import('eventsource').EventSourceInit} [options] - Configuration options.
 * @returns {EventSource}
 */
export function createEventSource(url, options = {}) {
  return new EventSource(url, options);
}

export { EventSource, ErrorEvent };

{
  "name": "sample-eventsource-errorevent",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-eventsource-errorevent",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "eventsource": "3.0.7"
      }
    },
    "node_modules/eventsource": {
      "version": "3.0.7",
      "resolved": "https://registry.npmjs.org/eventsource/-/eventsource-3.0.7.tgz",
      "integrity": "sha512-CRT1WTyuQoD771GW56XEZFQ/ZoSfWid1alKGDYMmkt2yl8UXrVR4pspqWNEcqKvVIzg6PAltWjxcSSPrboA4iA==",
      "license": "MIT",
      "dependencies": {
        "eventsource-parser": "^3.0.1"
      },
      "engines": {
        "node": ">=18.0.0"
      }
    },
    "node_modules/eventsource-parser": {
      "version": "3.1.1",
      "resolved": "https://registry.npmjs.org/eventsource-parser/-/eventsource-parser-3.1.1.tgz",
      "integrity": "sha512-EKN1vKAMcZ8MlYMpaNuxN6R9yakzH6uajHcHVTqWJzvu5pWw9DyhbP35HH8MVBQ+dZjAfDxk+A8NiR9KWaXiyQ==",
      "license": "MIT",
      "engines": {
        "node": ">=18.0.0"
      }
    }
  }
}

{
  "name": "sample-eventsource-errorevent",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "eventsource": "3.0.7"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify eventsource.ErrorEvent in pkg:npm/eventsource@3.0.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/eventsource@3.0.7"
  ],
  "symbols": [
    "eventsource.ErrorEvent"
  ]
}

import assert from 'node:assert/strict';
import http from 'node:http';
import util from 'node:util';
import { EventSource, ErrorEvent, createErrorEvent, createEventSource } from '../index.mjs';

// Contract 1: ErrorEvent extends Event and initializes type, message, and code properties from constructor options
const ev1 = createErrorEvent('error', { message: 'Failed to connect', code: 500 });
assert.ok(ev1 instanceof Event);
assert.ok(ev1 instanceof ErrorEvent);
assert.equal(ev1.type, 'error');
assert.equal(ev1.message, 'Failed to connect');
assert.equal(ev1.code, 500);
assert.equal(typeof ev1.timeStamp, 'number');

// Contract 2: ErrorEvent defaults code and message to undefined when initialized without options
const ev2 = createErrorEvent('error');
assert.ok(ev2 instanceof Event);
assert.ok(ev2 instanceof ErrorEvent);
assert.equal(ev2.type, 'error');
assert.equal(ev2.message, undefined);
assert.equal(ev2.code, undefined);

// Contract 3: ErrorEvent custom inspection formats properties including type, message, and code
const ev3 = createErrorEvent('error', { message: 'Custom inspect test', code: 404 });
const inspected = util.inspect(ev3);
assert.ok(inspected.includes('Custom inspect test'));
assert.ok(inspected.includes('404'));
assert.ok(inspected.includes('error'));

// Contract 4: EventSource dispatches ErrorEvent instance to onerror callback with HTTP error code on HTTP failure
await new Promise((resolve, reject) => {
  const server = http.createServer((req, res) => {
    res.writeHead(503, { 'Content-Type': 'text/plain' });
    res.end('Service Unavailable');
  });

  server.listen(0, '127.0.0.1', () => {
    const port = server.address().port;
    const es = createEventSource(`http://127.0.0.1:${port}/sse`);

    es.onerror = (ev) => {
      try {
        assert.ok(ev instanceof ErrorEvent, 'Event should be instance of ErrorEvent');
        assert.equal(ev.type, 'error');
        assert.equal(ev.code, 503);
        es.close();
        server.close(() => resolve());
      } catch (err) {
        es.close();
        server.close(() => reject(err));
      }
    };
  });
});

// Contract 5: EventSource dispatches ErrorEvent via addEventListener on connection failure
await new Promise((resolve, reject) => {
  const server = http.createServer((req, res) => {
    res.destroy();
  });

  server.listen(0, '127.0.0.1', () => {
    const port = server.address().port;
    const es = createEventSource(`http://127.0.0.1:${port}/sse`);

    es.addEventListener('error', (ev) => {
      try {
        assert.ok(ev instanceof ErrorEvent, 'Event should be instance of ErrorEvent');
        assert.equal(ev.type, 'error');
        es.close();
        server.close(() => resolve());
      } catch (err) {
        es.close();
        server.close(() => reject(err));
      }
    });
  });
});

console.log('Contract tests passed successfully.');