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48 lines
1.2 KiB
48 lines
1.2 KiB
'use strict';
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const common = require('../common');
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const EventEmitter = require('events');
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const assert = require('assert');
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const myEE = new EventEmitter();
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let m = 0;
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// This one comes last.
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myEE.on('foo', common.mustCall(() => assert.strictEqual(m, 2)));
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// This one comes second.
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myEE.prependListener('foo', common.mustCall(() => assert.strictEqual(m++, 1)));
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// This one comes first.
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myEE.prependOnceListener('foo',
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common.mustCall(() => assert.strictEqual(m++, 0)));
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myEE.emit('foo');
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// Verify that the listener must be a function
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assert.throws(() => {
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const ee = new EventEmitter();
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ee.prependOnceListener('foo', null);
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}, /^TypeError: "listener" argument must be a function$/);
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// Test fallback if prependListener is undefined.
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const stream = require('stream');
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const util = require('util');
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delete EventEmitter.prototype.prependListener;
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function Writable() {
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this.writable = true;
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stream.Stream.call(this);
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}
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util.inherits(Writable, stream.Stream);
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function Readable() {
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this.readable = true;
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stream.Stream.call(this);
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}
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util.inherits(Readable, stream.Stream);
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const w = new Writable();
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const r = new Readable();
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r.pipe(w);
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