nodejs/test/parallel/test-event-emitter-max-list...

32 lines
916 B
JavaScript

// Flags: --no-warnings
// The flag suppresses stderr output but the warning event will still emit
'use strict';
const common = require('../common');
const events = require('events');
const assert = require('assert');
class FakeInput extends events.EventEmitter {
resume() {}
pause() {}
write() {}
end() {}
}
const e = new FakeInput();
e.setMaxListeners(1);
process.on('warning', common.mustCall((warning) => {
assert.ok(warning instanceof Error);
assert.strictEqual(warning.name, 'MaxListenersExceededWarning');
assert.strictEqual(warning.emitter, e);
assert.strictEqual(warning.count, 2);
assert.strictEqual(warning.type, 'event-type');
assert.ok(warning.message.includes(
'2 event-type listeners added to [FakeInput].'));
}));
e.on('event-type', () => {});
e.on('event-type', () => {}); // Trigger warning.
e.on('event-type', () => {}); // Verify that warning is emitted only once.