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'use strict';
const common = require('../common');
const EventEmitter = require('events');
const assert = require('assert');
const myEE = new EventEmitter();
let m = 0;
// This one comes last.
myEE.on('foo', common.mustCall(() => assert.strictEqual(m, 2)));
// This one comes second.
myEE.prependListener('foo', common.mustCall(() => assert.strictEqual(m++, 1)));
// This one comes first.
myEE.prependOnceListener('foo',
common.mustCall(() => assert.strictEqual(m++, 0)));
myEE.emit('foo');
// Verify that the listener must be a function
common.expectsError(() => {
const ee = new EventEmitter();
ee.prependOnceListener('foo', null);
}, {
code: 'ERR_INVALID_ARG_TYPE',
type: TypeError,
message: 'The "listener" argument must be of type Function. ' +
'Received type object'
});
// Test fallback if prependListener is undefined.
const stream = require('stream');
delete EventEmitter.prototype.prependListener;
function Writable() {
this.writable = true;
stream.Stream.call(this);
}
Object.setPrototypeOf(Writable.prototype, stream.Stream.prototype);
Object.setPrototypeOf(Writable, stream.Stream);
function Readable() {
this.readable = true;
stream.Stream.call(this);
}
Object.setPrototypeOf(Readable.prototype, stream.Stream.prototype);
Object.setPrototypeOf(Readable, stream.Stream);
const w = new Writable();
const r = new Readable();
r.pipe(w);
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