node/test/parallel/test-event-emitter-max-listeners.js

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'use strict';
const common = require('../common');
const events = require('events');
const e = new events.EventEmitter();

e.on('maxListeners', common.mustCall());

// Should not corrupt the 'maxListeners' queue.
e.setMaxListeners(42);

const throwsObjs = [NaN, -1, 'and even this'];

for (const obj of throwsObjs) {
  common.expectsError(
    () => e.setMaxListeners(obj),
    {
      code: 'ERR_OUT_OF_RANGE',
      type: TypeError,
      message: 'The "n" argument is out of range'
    }
  );

  common.expectsError(
    () => events.defaultMaxListeners = obj,
    {
      code: 'ERR_OUT_OF_RANGE',
      type: TypeError,
      message: 'The "defaultMaxListeners" argument is out of range'
    }
  );
}

e.emit('maxListeners');