node/test/simple/test-stream-push-order.js

// Copyright Joyent, Inc. and other Node contributors.
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//
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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var common = require('../common.js');
var Readable = require('stream').Readable;
var assert = require('assert');

var s = new Readable({
  highWaterMark: 20,
  encoding: 'ascii'
});

var list = ['1', '2', '3', '4', '5', '6'];

s._read = function (n) {
  var one = list.shift();
  if (!one) {
    s.push(null);
  } else {
    var two = list.shift();
    s.push(one);
    s.push(two);
  }
};

var v = s.read(0);

// ACTUALLY [1, 3, 5, 6, 4, 2]

process.on("exit", function () {
  assert.deepEqual(s._readableState.buffer,
                   ['1', '2', '3', '4', '5', '6']);
  console.log("ok");
});