Implement WebSocketDeflater.

net/websockets/websocket_deflater_test.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/websockets/websocket_deflater.h"
+
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"

[Adam Rice, 2013/08/30 13:20:13]

scoped_ptr.h and gmock.h are not used.

[yhirano, 2013/09/02 02:01:12]

Done.

+#include "net/base/io_buffer.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+

[Adam Rice, 2013/08/30 13:20:13]

Nitpick: it would be better to add an anonymous namespace inside net, just to be
absolutely sure that no namespace collisions can happen.

[yhirano, 2013/09/02 02:01:12]

Done.

+TEST(WebSocketDeflaterTest, Construct) {
+  WebSocketDeflater deflater(8, WebSocketDeflater::TAKE_OVER_CONTEXT);
+
+  scoped_refptr<IOBufferWithSize> actual = deflater.Finish();
+  ASSERT_TRUE(actual);
+  EXPECT_EQ(std::string("\x02\00", 2),
+            std::string(actual->data(), actual->size()));

[Adam Rice, 2013/08/30 13:20:13]

This line is repeated so many times that I would probably make a function at the
top like

std::string IOBufferToString(const scoped_refptr<IOBufferWithSize>& iobuffer) { 
  return std::string(iobuffer->data(), iobuffer->size());
}

to reduce the repetition.

[yhirano, 2013/09/02 02:01:12]

Done.

+}
+
+TEST(WebSocketDeflaterTest, DeflateHelloTakeOverContext) {
+  WebSocketDeflater deflater(15, WebSocketDeflater::TAKE_OVER_CONTEXT);
+  scoped_refptr<IOBufferWithSize> actual1, actual2;
+
+  ASSERT_TRUE(deflater.AddBytes("Hello", strlen("Hello")));
+  actual1 = deflater.Finish();
+  ASSERT_TRUE(actual1);
+  EXPECT_EQ(std::string("\xf2\x48\xcd\xc9\xc9\x07\x00", 7),
+            std::string(actual1->data(), actual1->size()));
+
+  ASSERT_TRUE(deflater.AddBytes("Hello", strlen("Hello")));
+  actual2 = deflater.Finish();
+  ASSERT_TRUE(actual2);
+  EXPECT_EQ(std::string("\xf2\x00\x11\x00\x00", 5),
+            std::string(actual2->data(), actual2->size()));
+}
+
+TEST(WebSocketDeflaterTest, DeflateHelloDoNotTakeOverContext) {
+  WebSocketDeflater deflater(15, WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT);
+  scoped_refptr<IOBufferWithSize> actual1, actual2;
+
+  ASSERT_TRUE(deflater.AddBytes("Hello", strlen("Hello")));
+  actual1 = deflater.Finish();
+  ASSERT_TRUE(actual1);
+  EXPECT_EQ(std::string("\xf2\x48\xcd\xc9\xc9\x07\x00", 7),
+            std::string(actual1->data(), actual1->size()));
+
+  ASSERT_TRUE(deflater.AddBytes("Hello", strlen("Hello")));
+  actual2 = deflater.Finish();
+  ASSERT_TRUE(actual2);
+  EXPECT_EQ(std::string("\xf2\x48\xcd\xc9\xc9\x07\x00", 7),
+            std::string(actual2->data(), actual2->size()));
+}
+
+TEST(WebSocketDeflaterTest, MultipleAddBytesCalls) {
+  WebSocketDeflater deflater(15, WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT);
+  std::string input(32, 'a');
+  scoped_refptr<IOBufferWithSize> actual;
+
+  for (size_t i = 0; i < input.size(); ++i) {
+    ASSERT_TRUE(deflater.AddBytes(&input[i], 1));
+  }
+  actual = deflater.Finish();
+  ASSERT_TRUE(actual);
+  EXPECT_EQ(std::string("\x4a\x4c\xc4\x0f\x00\x00", 6),
+            std::string(actual->data(), actual->size()));
+}
+
+TEST(WebSocketDeflaterTest, WindowBits8) {
+  WebSocketDeflater deflater8(8, WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT);
+  // Set the head and tail of |input| so that back-reference
+  // can be used if the window size is sufficiently-large.
+  std::string input =
+      std::string(64, 'b') + std::string(1024, 'a') + std::string(64, 'b');

[Adam Rice, 2013/08/30 13:20:13]

64 'b's is too easy to compress, so the back reference does not gain us very
much. I suggest you use a shorter, more random string at the beginning and the
end. For example, define

const char kWord[] = "Chromium";

at the top of the file and then

std::string input = kWord + std::string(1024, 'a') + kWord;

in the test. This should make it clearer that the larger window size gives
better compression.

Also, you only actually need 256 'a' characters to break the 8-bit window.

[yhirano, 2013/09/02 02:01:12]

Done.

+  scoped_refptr<IOBufferWithSize> actual8;
+
+  ASSERT_TRUE(deflater8.AddBytes(input.data(), input.size()));
+  actual8 = deflater8.Finish();
+  ASSERT_TRUE(actual8);
+  EXPECT_EQ(std::string("JJ\xa2\x0c$\x8e\x82Q0\nF,H\xa2\x10\x00\x00", 17),
+            std::string(actual8->data(), actual8->size()));
+}
+
+TEST(WebSocketDeflaterTest, WindowBits15) {

[Adam Rice, 2013/08/30 13:20:13]

You only actually need 11 or 12 window bits to get the best compression here. If
you reduce the padding 'a's to 256, then you only need 10 window bits.

[yhirano, 2013/09/02 02:01:12]

Done.

+  WebSocketDeflater deflater15(15, WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT);
+  // Set the head and tail of |input| so that back-reference
+  // can be used if the window size is sufficiently-large.
+  std::string input =
+      std::string(64, 'b') + std::string(1024, 'a') + std::string(64, 'b');
+  scoped_refptr<IOBufferWithSize> actual15;
+
+  ASSERT_TRUE(deflater15.AddBytes(input.data(), input.size()));
+  actual15 = deflater15.Finish();
+  ASSERT_TRUE(actual15);
+  EXPECT_EQ(std::string("JJ\xa2\x0c$\x8e\x82Q0\nF,\xa0\xb0\xf8H\x02\x00", 18),
+            std::string(actual15->data(), actual15->size()));
+}
+
+}  // namespace net