Make CopyOnWriteBuffer keep capacity

webrtc/base/copyonwritebuffer_unittest.cc

 /*
  *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 131 matching lines @@
 }
 
 TEST(CopyOnWriteBufferTest, TestSetDataEmpty) {
   CopyOnWriteBuffer buf;
   buf.SetData(static_cast<const uint8_t*>(nullptr), 0u);
   EXPECT_EQ(buf.size(), 0u);
   EXPECT_EQ(buf.capacity(), 0u);
   EXPECT_EQ(buf.data(), nullptr);
 }
 
+TEST(CopyOnWriteBufferTest, SetDataSmallerCapacityCauseNoReallocation) {

[kwiberg-webrtc, 2016/09/09 08:55:14]

"Causes". Or even better, "DoesntCause"

[danilchap, 2016/09/09 11:21:17]

Done.

+  CopyOnWriteBuffer buf1(kTestData, 3, 10);
+  const uint8_t* raw = buf1.cdata();

[kwiberg-webrtc, 2016/09/09 08:55:14]

You can make the pointer const too.

[danilchap, 2016/09/09 11:21:17]

Done.

+
+  buf1.SetData(kTestData, 2, 5);
+
+  EXPECT_EQ(2U, buf1.size());

[kwiberg-webrtc, 2016/09/09 08:55:13]

Lower-case "u".

[danilchap, 2016/09/09 11:21:17]

for local consistency, Done.
but globally prefer uppercase just because one of examples in style guide use
uppercase suffix. (none use lowercase there)

[kwiberg-webrtc, 2016/09/09 12:59:14]

OK.
"u" is better than "U" because it's more visually distinct from a digit. That
the style guide happens to use "U" in an unrelated example isn't a good enough
reason to use "U", IMO.

+  EXPECT_LE(5U, buf1.capacity());
+  EXPECT_EQ(raw, buf1.cdata());
+}
+
+TEST(CopyOnWriteBufferTest, SetDataSmallerCapacityOnShared) {
+  CopyOnWriteBuffer buf1(kTestData, 3, 10);
+  CopyOnWriteBuffer buf2(buf1);
+  EnsureBuffersShareData(buf1, buf2);
+
+  buf2.SetData(kTestData, 2, 5);
+
+  EnsureBuffersDontShareData(buf1, buf2);
+  EXPECT_EQ(2U, buf2.size());
+  EXPECT_LE(5U, buf2.capacity());
+}
+
+TEST(CopyOnWriteBufferTest, SetDataLargerCapacity) {
+  CopyOnWriteBuffer buf1(kTestData, 3, 10);
+
+  buf1.SetData(kTestData, 2, 15);
+
+  EXPECT_EQ(2U, buf1.size());
+  EXPECT_LE(15U, buf1.capacity());
+}
+
+TEST(CopyOnWriteBufferTest, SetDataOnEmpty) {
+  CopyOnWriteBuffer buf1;
+
+  buf1.SetData(kTestData, 2, 15);
+
+  EXPECT_EQ(2U, buf1.size());
+  EXPECT_LE(15U, buf1.capacity());
+}

[kwiberg-webrtc, 2016/09/09 08:55:13]

In order to put the more fundamental tests first, reorder these from 1234 to
3412 or something like that?

[danilchap, 2016/09/09 11:21:17]

Done.
Reordered 4312.

+
 TEST(CopyOnWriteBufferTest, TestEnsureCapacity) {
   CopyOnWriteBuffer buf1(kTestData, 3, 10);
   CopyOnWriteBuffer buf2(buf1);
 
   // Smaller than existing capacity -> no change and still same contents.
   buf2.EnsureCapacity(8);
   EnsureBuffersShareData(buf1, buf2);
   EXPECT_EQ(buf1.size(), 3u);
   EXPECT_EQ(buf1.capacity(), 10u);
   EXPECT_EQ(buf2.size(), 3u);
@@ skipping 89 matching lines @@
     buf1[i] = kTestData[i] + 1;
   }
   EXPECT_EQ(buf1.size(), 3u);
   EXPECT_EQ(buf1.capacity(), 10u);
   EXPECT_EQ(buf2.size(), 3u);
   EXPECT_EQ(buf2.capacity(), 10u);
   EXPECT_EQ(0, memcmp(buf2.cdata(), kTestData, 3));
 }
 
 }  // namespace rtc