fix: make EventSource properties enumerable (nodejs#2987)

* make eventsource properties enumberable

* Use kEnumerableProperty for eventsource immutable fields

* Apply suggestions from code review

* Apply suggestions from code review

---------

Co-authored-by: Aras Abbasi <aras.abbasi@googlemail.com>

lib/web/eventsource/eventsource.js

@@ -10,6 +10,7 @@ const { parseMIMEType } = require('../fetch/data-url')
 const { MessageEvent } = require('../websocket/events')
 const { isNetworkError } = require('../fetch/response')
 const { delay } = require('./util')
+const { kEnumerableProperty } = require('../../core/util')
 
 let experimentalWarned = false
 
@@ -459,6 +460,16 @@ const constantsPropertyDescriptors = {
 Object.defineProperties(EventSource, constantsPropertyDescriptors)
 Object.defineProperties(EventSource.prototype, constantsPropertyDescriptors)
 
+Object.defineProperties(EventSource.prototype, {
+  close: kEnumerableProperty,
+  onerror: kEnumerableProperty,
+  onmessage: kEnumerableProperty,
+  onopen: kEnumerableProperty,
+  readyState: kEnumerableProperty,
+  url: kEnumerableProperty,
+  withCredentials: kEnumerableProperty
+})
+
 webidl.converters.EventSourceInitDict = webidl.dictionaryConverter([
   { key: 'withCredentials', converter: webidl.converters.boolean, defaultValue: false }
 ])

test/eventsource/eventsource-properties.js

@@ -0,0 +1,15 @@
+'use strict'
+
+const { test } = require('node:test')
+const assert = require('node:assert')
+const { EventSource } = require('../..') // assuming the test is in test/eventsource/
+
+test('EventSource.prototype properties are configured correctly', () => {
+  const props = Object.entries(Object.getOwnPropertyDescriptors(EventSource.prototype))
+
+  for (const [key, value] of props) {
+    if (key !== 'constructor') {
+      assert(value.enumerable, `${key} is not enumerable`)
+    }
+  }
+})