test/parallel/test-event-emitter-invalid-listener.js


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'use strict';

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

const eventsMethods = ['on', 'once', 'removeListener', 'prependOnceListener'];

// Verify that the listener must be a function for events methods
for (const method of eventsMethods) {
  assert.throws(() => {
    const ee = new EventEmitter();
    ee[method]('foo', null);
  }, {
    code: 'ERR_INVALID_ARG_TYPE',
    name: 'TypeError',
    message: 'The "listener" argument must be of type function. ' +
             'Received null',
  }, `event.${method}('foo', null) should throw the proper error`);
}