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stream: fix eventNames() to not return not defined events
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PR-URL: #51331
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
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IlyasShabi authored and marco-ippolito committed Feb 29, 2024
1 parent 7543e77 commit 5b06af7
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11 changes: 11 additions & 0 deletions lib/internal/streams/legacy.js
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
const {
ArrayIsArray,
ObjectSetPrototypeOf,
ReflectOwnKeys,
} = primordials;

const EE = require('events');
Expand Down Expand Up @@ -93,6 +94,16 @@ Stream.prototype.pipe = function(dest, options) {
return dest;
};

Stream.prototype.eventNames = function eventNames() {
const names = [];
for (const key of ReflectOwnKeys(this._events)) {
if (typeof this._events[key] === 'function' || (ArrayIsArray(this._events[key]) && this._events[key].length > 0)) {
names.push(key);
}
}
return names;
};

function prependListener(emitter, event, fn) {
// Sadly this is not cacheable as some libraries bundle their own
// event emitter implementation with them.
Expand Down
42 changes: 42 additions & 0 deletions test/parallel/test-stream-event-names.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
'use strict';

require('../common');
const assert = require('assert');
const { Readable, Writable, Duplex } = require('stream');

{
const stream = new Readable();
assert.strictEqual(stream.eventNames().length, 0);
}

{
const stream = new Readable();
stream.on('foo', () => {});
stream.on('data', () => {});
stream.on('error', () => {});
assert.deepStrictEqual(stream.eventNames(), ['error', 'data', 'foo']);
}

{
const stream = new Writable();
assert.strictEqual(stream.eventNames().length, 0);
}

{
const stream = new Writable();
stream.on('foo', () => {});
stream.on('drain', () => {});
stream.on('prefinish', () => {});
assert.deepStrictEqual(stream.eventNames(), ['prefinish', 'drain', 'foo']);
}
{
const stream = new Duplex();
assert.strictEqual(stream.eventNames().length, 0);
}

{
const stream = new Duplex();
stream.on('foo', () => {});
stream.on('finish', () => {});
assert.deepStrictEqual(stream.eventNames(), ['finish', 'foo']);
}

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