test-event-emitter-check-listener-leaks.js

// deno-fmt-ignore-file
// deno-lint-ignore-file

// Copyright Joyent and Node contributors. All rights reserved. MIT license.
// Taken from Node 16.13.0
// This file is automatically generated by "node/_tools/setup.ts". Do not modify this file manually

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'use strict';

const common = require('../common');
const assert = require('assert');
const events = require('events');

// default
{
  const e = new events.EventEmitter();

  for (let i = 0; i < 10; i++) {
    e.on('default', common.mustNotCall());
  }
  assert.ok(!e._events.default.hasOwnProperty('warned'));
  e.on('default', common.mustNotCall());
  assert.ok(e._events.default.warned);

  // symbol
  const symbol = Symbol('symbol');
  e.setMaxListeners(1);
  e.on(symbol, common.mustNotCall());
  assert.ok(!e._events[symbol].hasOwnProperty('warned'));
  e.on(symbol, common.mustNotCall());
  assert.ok(e._events[symbol].hasOwnProperty('warned'));

  // specific
  e.setMaxListeners(5);
  for (let i = 0; i < 5; i++) {
    e.on('specific', common.mustNotCall());
  }
  assert.ok(!e._events.specific.hasOwnProperty('warned'));
  e.on('specific', common.mustNotCall());
  assert.ok(e._events.specific.warned);

  // only one
  e.setMaxListeners(1);
  e.on('only one', common.mustNotCall());
  assert.ok(!e._events['only one'].hasOwnProperty('warned'));
  e.on('only one', common.mustNotCall());
  assert.ok(e._events['only one'].hasOwnProperty('warned'));

  // unlimited
  e.setMaxListeners(0);
  for (let i = 0; i < 1000; i++) {
    e.on('unlimited', common.mustNotCall());
  }
  assert.ok(!e._events.unlimited.hasOwnProperty('warned'));
}

// process-wide
{
  events.EventEmitter.defaultMaxListeners = 42;
  const e = new events.EventEmitter();

  for (let i = 0; i < 42; ++i) {
    e.on('fortytwo', common.mustNotCall());
  }
  assert.ok(!e._events.fortytwo.hasOwnProperty('warned'));
  e.on('fortytwo', common.mustNotCall());
  assert.ok(e._events.fortytwo.hasOwnProperty('warned'));
  delete e._events.fortytwo.warned;

  events.EventEmitter.defaultMaxListeners = 44;
  e.on('fortytwo', common.mustNotCall());
  assert.ok(!e._events.fortytwo.hasOwnProperty('warned'));
  e.on('fortytwo', common.mustNotCall());
  assert.ok(e._events.fortytwo.hasOwnProperty('warned'));
}

// But _maxListeners still has precedence over defaultMaxListeners
{
  events.EventEmitter.defaultMaxListeners = 42;
  const e = new events.EventEmitter();
  e.setMaxListeners(1);
  e.on('uno', common.mustNotCall());
  assert.ok(!e._events.uno.hasOwnProperty('warned'));
  e.on('uno', common.mustNotCall());
  assert.ok(e._events.uno.hasOwnProperty('warned'));

  // chainable
  assert.strictEqual(e, e.setMaxListeners(1));
}