Refactor composing report blocks for rtcp Sender/Receiver reports

webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report_unittest.cc

 /*
  *  Copyright (c) 2015 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 109 matching lines @@
   const size_t kMaxReportBlocks = (1 << 5) - 1;
   ReportBlock rb;
   for (size_t i = 0; i < kMaxReportBlocks; ++i) {
     rb.SetMediaSsrc(kRemoteSsrc + i);
     EXPECT_TRUE(rr.AddReportBlock(rb));
   }
   rb.SetMediaSsrc(kRemoteSsrc + kMaxReportBlocks);
   EXPECT_FALSE(rr.AddReportBlock(rb));
 }
 
+TEST(RtcpPacketReceiverReportTest, SetReportBlocksOverwritesOldBlocks) {

[eladalon, 2017/07/21 12:53:19]

nit: Checking by size only does not guarantee correctness completely. Suppose we
start with [1], and try to set([5, 6, 7]), I can imagine code that would
accidentally end up with [1, 6, 7], which would still pass the test. IMHO, it
wouldn't be overkill to check the members, too. Or is it difficult to do
comparison of the specific elements there?

[danilchap, 2017/07/21 17:11:14]

I lack imagination to see that code, but it's not too hard to check some values
in report blocks. Done.

+  ReceiverReport rr;
+  rr.AddReportBlock(ReportBlock());
+  ASSERT_EQ(rr.report_blocks().size(), 1u);
+
+  std::vector<ReportBlock> blocks(3);
+  EXPECT_TRUE(rr.SetReportBlocks(blocks));
+  EXPECT_EQ(rr.report_blocks().size(), 3u);
+}
+
+TEST(RtcpPacketReceiverReportTest, SetTooManyReportBlocks) {
+  ReceiverReport rr;
+  const size_t kMaxReportBlocks = (1 << 5) - 1;
+
+  std::vector<ReportBlock> blocks(kMaxReportBlocks);
+  EXPECT_TRUE(rr.SetReportBlocks(blocks));

[eladalon, 2017/07/21 12:53:19]

nit: Two tests here:
1. Max number of blocks accepted.
2. One more than max - rejected.

[danilchap, 2017/07/21 17:11:14]

renamed to document this test is about showing the limit.

+
+  blocks.push_back(ReportBlock());
+  EXPECT_FALSE(rr.SetReportBlocks(blocks));
+}
+
 }  // namespace webrtc