eventsource 3.0.7: EventSource

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/eventsource@3.0.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/eventsource@3.0.7
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:sha256:27b05d1f2852da43248c77d69324a8d2e072a9a19283d39763f468e5fcb9b5c6","constraints":{"executionContext":"node"},"contract":["EventSource exposes readyState constants CONNECTING (0), OPEN (1), and CLOSED (2)","EventSource initializes with CONNECTING readyState, the target URL, and default options","EventSource connects to an SSE endpoint and dispatches open event with readyState OPEN","EventSource receives and parses standard message events with event.data","EventSource receives and dispatches custom named events via addEventListener","EventSource.close() terminates the connection and transitions readyState to CLOSED"],"goal":"verify pkg:npm/eventsource@3.0.7","kind":"HOW","packages":["pkg:npm/eventsource@3.0.7"],"schemaVersion":1,"symbols":["EventSource"]},"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/eventsource@3.0.7"],"schemaVersion":1,"subject":"pkg:npm/eventsource@3.0.7","symbols":["EventSource"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-eventsource-verify",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-eventsource-verify",
      "version": "1.0.0",
      "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-verify",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "eventsource": "3.0.7"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/eventsource@3.0.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/eventsource@3.0.7"
  ],
  "symbols": [
    "EventSource"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert/strict';
import http from 'node:http';
import { EventSource } from 'eventsource';

// 1. EventSource exposes readyState constants CONNECTING (0), OPEN (1), and CLOSED (2)
{
  assert.equal(EventSource.CONNECTING, 0);
  assert.equal(EventSource.OPEN, 1);
  assert.equal(EventSource.CLOSED, 2);
}

// Helper to run offline HTTP SSE server for network contracts
async function createTestServer() {
  const server = http.createServer((req, res) => {
    res.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
    });
    res.write('event: custom-event\ndata: payload-data\n\n');
    res.write('data: line1\ndata: line2\n\n');
  });

  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
  const port = server.address().port;
  const url = `http://127.0.0.1:${port}/sse`;
  return { server, url };
}

const { server, url } = await createTestServer();

try {
  // 2. EventSource initializes with CONNECTING readyState, the target URL, and default options
  const es = new EventSource(url);
  assert.equal(es.readyState, EventSource.CONNECTING);
  assert.equal(es.url, url);
  assert.equal(es.withCredentials, false);
  assert.equal(es.CONNECTING, 0);
  assert.equal(es.OPEN, 1);
  assert.equal(es.CLOSED, 2);

  const receivedCustomEvents = [];
  const receivedMessages = [];

  await new Promise((resolve, reject) => {
    const timeout = setTimeout(() => {
      reject(new Error('Test timed out waiting for SSE events'));
    }, 5000);

    // 3. EventSource connects to an SSE endpoint and dispatches open event with readyState OPEN
    es.addEventListener('open', () => {
      assert.equal(es.readyState, EventSource.OPEN);
    });

    // 5. EventSource receives and dispatches custom named events via addEventListener
    es.addEventListener('custom-event', (event) => {
      receivedCustomEvents.push(event.data);
    });

    // 4. EventSource receives and parses standard message events with event.data
    es.addEventListener('message', (event) => {
      receivedMessages.push(event.data);
      if (receivedCustomEvents.length === 1 && receivedMessages.length === 1) {
        clearTimeout(timeout);
        resolve();
      }
    });

    es.addEventListener('error', (err) => {
      clearTimeout(timeout);
      reject(err);
    });
  });

  assert.deepEqual(receivedCustomEvents, ['payload-data']);
  assert.deepEqual(receivedMessages, ['line1\nline2']);

  // 6. EventSource.close() terminates the connection and transitions readyState to CLOSED
  es.close();
  assert.equal(es.readyState, EventSource.CLOSED);
} finally {
  await new Promise((resolve) => server.close(resolve));
}