added writer to clarify test intentions. not sure if i'm going to use

it in actual library

test/writer-tests.js

@@ -0,0 +1,115 @@
+require(__dirname + "/test-helper");
+
+var BufferList = function() {
+  this.buffers = [];
+};
+
+BufferList.prototype.add = function(buffer, front) {
+  this.buffers[front ? "unshift" : "push"](buffer);
+  return this;
+};
+
+BufferList.prototype.addInt16 = function(val, front) {
+  return this.add(Buffer([(val >>> 8),(val >>> 0)]),front);
+};
+
+BufferList.prototype.getByteLength = function(initial) {
+  return this.buffers.reduce(function(previous, current){
+    return previous + current.length;
+  },initial || 0);
+};
+
+BufferList.prototype.addInt32 = function(val, first) {
+  return this.add(Buffer([
+    (val >>> 24),
+    (val >>> 16),
+    (val >>> 8),
+    (val >>> 0)
+  ]),first);
+};
+
+BufferList.prototype.addCString = function(val) {
+  return this.add(Buffer(val + '\0','utf8'));
+};
+
+BufferList.prototype.join = function(appendLength, char) {
+  var length = this.getByteLength();
+  if(appendLength) {
+    this.addInt32(length+4, true);
+    return this.join(false, char);
+  }
+  if(char) {
+    this.buffers.unshift(Buffer(char,'utf8'));
+    length++;
+  }
+  var result = Buffer(length);
+  var index = 0;
+  this.buffers.forEach(function(buffer) {
+    buffer.copy(result, index, 0);
+    index += buffer.length;
+  });
+  return result;
+};
+
+assert.equalBuffers = function(actual, expected) {
+  if(actual.length != expected.length) {
+    console.log(actual);
+    console.log(expected);
+    assert.equal(actual.length, expected.length);
+  }
+  for(var i = 0; i < actual.length; i++) {
+    if(actual[i] != expected[i]) {
+      console.log(actual);
+      console.log(expected);
+    }
+    assert.equal(actual[i],expected[i]);
+  }
+}
+
+BufferList.prototype.compare = function(expected) {
+  var buf = this.join();
+  assert.equalBuffers(buf, expected);
+};
+
+test('adds int16', function() {
+  new BufferList().addInt16(5).compare([0, 5]);
+});
+
+test('adds two int16s', function() {
+  new BufferList().addInt16(5).addInt16(3).compare([0,5,0,3]);
+});
+
+test('adds int32', function() {
+  new BufferList().addInt32(1).compare([0,0,0,1]);
+  new BufferList().addInt32(1).addInt32(3).compare([0,0,0,1,0,0,0,3]);
+});
+
+test('adds CStrings', function() {
+  new BufferList().addCString('').compare([0]);
+  new BufferList().addCString('!!').compare([33,33,0]);
+  new BufferList().addCString('!').addCString('!').compare([33,0,33,0]);
+});
+
+test('computes length', function() {
+  var buf = new BufferList().join(true);
+  assert.equalBuffers(buf, [0,0,0,4]);
+});
+
+test('appends character', function() {
+  var buf = new BufferList().join(false,'!');
+  assert.equalBuffers(buf,[33]);
+});
+
+test('appends char and length', function() {
+  var buf = new BufferList().join(true,'!');
+  assert.equalBuffers(buf,[33,0,0,0,4]);
+});
+
+test('does complicated buffer', function() {
+  var buf = new BufferList()
+    .addInt32(1)
+    .addInt16(2)
+    .addCString('!')
+    .join(true,'!');
+  assert.equalBuffers(buf, [33, 0, 0, 0, 0x0c, 0, 0, 0, 1, 0, 2, 33, 0]);
+});