test-zlib.js

// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

var assert = require('assert');
var zlib = require('../');
var path = require('path');

var zlibPairs =
    [[zlib.Deflate, zlib.Inflate],
     [zlib.Gzip, zlib.Gunzip],
     [zlib.Deflate, zlib.Unzip],
     [zlib.Gzip, zlib.Unzip],
     [zlib.DeflateRaw, zlib.InflateRaw]];

// how fast to trickle through the slowstream
var trickle = [128, 1024, 1024 * 1024];

// tunable options for zlib classes.

// several different chunk sizes
var chunkSize = [128, 1024, 1024 * 16, 1024 * 1024];

// this is every possible value.
var level = [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
var windowBits = [8, 9, 10, 11, 12, 13, 14, 15];
var memLevel = [1, 2, 3, 4, 5, 6, 7, 8, 9];
var strategy = [0, 1, 2, 3, 4];

// it's nice in theory to test every combination, but it
// takes WAY too long.  Maybe a pummel test could do this?
if (!process.env.PUMMEL) {
  trickle = [1024];
  chunkSize = [1024 * 16];
  level = [6];
  memLevel = [8];
  windowBits = [15];
  strategy = [0];
}

var fs = require('fs');

if (process.env.FAST) {
  zlibPairs = [[zlib.Gzip, zlib.Unzip]];
}

var tests = {
  'person.jpg': fs.readFileSync(__dirname + '/fixtures/person.jpg'),
  'elipses.txt': fs.readFileSync(__dirname + '/fixtures/elipses.txt'),
  'empty.txt': fs.readFileSync(__dirname + '/fixtures/empty.txt')
};

var util = require('util');
var stream = require('stream');


// stream that saves everything
function BufferStream() {
  this.chunks = [];
  this.length = 0;
  this.writable = true;
  this.readable = true;
}

util.inherits(BufferStream, stream.Stream);

BufferStream.prototype.write = function(c) {
  this.chunks.push(c);
  this.length += c.length;
  return true;
};

BufferStream.prototype.end = function(c) {
  if (c) this.write(c);
  // flatten
  var buf = new Buffer(this.length);
  var i = 0;
  this.chunks.forEach(function(c) {
    c.copy(buf, i);
    i += c.length;
  });
  this.emit('data', buf);
  this.emit('end');
  return true;
};


function SlowStream(trickle) {
  this.trickle = trickle;
  this.offset = 0;
  this.readable = this.writable = true;
}

util.inherits(SlowStream, stream.Stream);

SlowStream.prototype.write = function() {
  throw new Error('not implemented, just call ss.end(chunk)');
};

SlowStream.prototype.pause = function() {
  this.paused = true;
  this.emit('pause');
};

SlowStream.prototype.resume = function() {
  var self = this;
  if (self.ended) return;
  self.emit('resume');
  if (!self.chunk) return;
  self.paused = false;
  emit();
  function emit() {
    if (self.paused) return;
    if (self.offset >= self.length) {
      self.ended = true;
      return self.emit('end');
    }
    var end = Math.min(self.offset + self.trickle, self.length);
    var c = self.chunk.slice(self.offset, end);
    self.offset += c.length;
    self.emit('data', c);
    process.nextTick(emit);
  }
};

SlowStream.prototype.end = function(chunk) {
  // walk over the chunk in blocks.
  var self = this;
  self.chunk = chunk;
  self.length = chunk.length;
  self.resume();
  return self.ended;
};



// for each of the files, make sure that compressing and
// decompressing results in the same data, for every combination
// of the options set above.
var tape = require('tape');

Object.keys(tests).forEach(function(file) {
  var test = tests[file];
  chunkSize.forEach(function(chunkSize) {
    trickle.forEach(function(trickle) {
      windowBits.forEach(function(windowBits) {
        level.forEach(function(level) {
          memLevel.forEach(function(memLevel) {
            strategy.forEach(function(strategy) {
              zlibPairs.forEach(function(pair) {
                var Def = pair[0];
                var Inf = pair[1];
                var opts = { 
                  level: level,
                  windowBits: windowBits,
                  memLevel: memLevel,
                  strategy: strategy
                };
                
                var msg = file + ' ' +
                    chunkSize + ' ' +
                    JSON.stringify(opts) + ' ' +
                    Def.name + ' -> ' + Inf.name;
                
                tape('zlib ' + msg, function(t) {
                  t.plan(1);
                  
                  var def = new Def(opts);
                  var inf = new Inf(opts);
                  var ss = new SlowStream(trickle);
                  var buf = new BufferStream();

                  // verify that the same exact buffer comes out the other end.
                  buf.on('data', function(c) {
                    t.deepEqual(c, test);
                  });

                  // the magic happens here.
                  ss.pipe(def).pipe(inf).pipe(buf);
                  ss.end(test);
                });
              });
            });
          });
        });
      });
    }); 
  });
});