Make CopyOnWriteBuffer keep capacity

webrtc/base/copyonwritebuffer_unittest.cc

Index: webrtc/base/copyonwritebuffer_unittest.cc
diff --git a/webrtc/base/copyonwritebuffer_unittest.cc b/webrtc/base/copyonwritebuffer_unittest.cc
index dbf59f7718f2779f0dff9bc0c3c26d79918a00c5..93070ef47fc7407deeac75d4d8c8385951f9c37f 100644
--- a/webrtc/base/copyonwritebuffer_unittest.cc
+++ b/webrtc/base/copyonwritebuffer_unittest.cc
@@ -149,6 +149,47 @@ TEST(CopyOnWriteBufferTest, TestSetDataEmpty) {
   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);