node/test/parallel/test-stream-readable-event.js

'use strict';
require('../common');
var assert = require('assert');

var Readable = require('stream').Readable;

(function first() {
  // First test, not reading when the readable is added.
  // make sure that on('readable', ...) triggers a readable event.
  var r = new Readable({
    highWaterMark: 3
  });

  var _readCalled = false;
  r._read = function(n) {
    _readCalled = true;
  };

  // This triggers a 'readable' event, which is lost.
  r.push(new Buffer('blerg'));

  var caughtReadable = false;
  setTimeout(function() {
    // we're testing what we think we are
    assert(!r._readableState.reading);
    r.on('readable', function() {
      caughtReadable = true;
    });
  });

  process.on('exit', function() {
    // we're testing what we think we are
    assert(!_readCalled);

    assert(caughtReadable);
    console.log('ok 1');
  });
})();

(function second() {
  // second test, make sure that readable is re-emitted if there's
  // already a length, while it IS reading.

  var r = new Readable({
    highWaterMark: 3
  });

  var _readCalled = false;
  r._read = function(n) {
    _readCalled = true;
  };

  // This triggers a 'readable' event, which is lost.
  r.push(new Buffer('bl'));

  var caughtReadable = false;
  setTimeout(function() {
    // assert we're testing what we think we are
    assert(r._readableState.reading);
    r.on('readable', function() {
      caughtReadable = true;
    });
  });

  process.on('exit', function() {
    // we're testing what we think we are
    assert(_readCalled);

    assert(caughtReadable);
    console.log('ok 2');
  });
})();

(function third() {
  // Third test, not reading when the stream has not passed
  // the highWaterMark but *has* reached EOF.
  var r = new Readable({
    highWaterMark: 30
  });

  var _readCalled = false;
  r._read = function(n) {
    _readCalled = true;
  };

  // This triggers a 'readable' event, which is lost.
  r.push(new Buffer('blerg'));
  r.push(null);

  var caughtReadable = false;
  setTimeout(function() {
    // assert we're testing what we think we are
    assert(!r._readableState.reading);
    r.on('readable', function() {
      caughtReadable = true;
    });
  });

  process.on('exit', function() {
    // we're testing what we think we are
    assert(!_readCalled);

    assert(caughtReadable);
    console.log('ok 3');
  });
})();