Fix packetization logic to leave space for extensions in the last packet

webrtc/modules/rtp_rtcp/source/rtp_format_video_generic_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_format_video_generic_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_format_video_generic_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtp_format_video_generic_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..129ae24d904486a11c9357c0dce4bd525c5bed5b
--- /dev/null
+++ b/webrtc/modules/rtp_rtcp/source/rtp_format_video_generic_unittest.cc
@@ -0,0 +1,80 @@
+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/modules/include/module_common_types.h"
+#include "webrtc/modules/rtp_rtcp/mocks/mock_rtp_rtcp.h"
+#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_format_video_generic.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_packet_to_send.h"
+#include "webrtc/test/gmock.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+namespace RtpFormatVideoGeneric {

[danilchap, 2017/05/12 18:56:15]

do not use this namespace

[ilnik, 2017/05/15 09:38:33]

Done.

+namespace {
+
+using ::testing::ElementsAreArray;
+
+constexpr RtpPacketToSend::ExtensionManager* kNoExtensions = nullptr;
+const size_t kMaxPayloadSize = 1200;
+// const size_t kGenericHeaderLen = 1;
+
+uint8_t test_payload_buffer[kMaxPayloadSize];
+
+void VerifyPacketsSizes(size_t payload_length, size_t max_payload_length,
+                       size_t extensions_length,
+                       std::vector<size_t> expected_sizes) {

[danilchap, 2017/05/12 18:56:15]

Likely it is more readable when helpers do not contain test logic.
E.g.
std::vector<size_t> NextPacketFillPayloadSizes(RtpPacketizerGeneric* packetizer)
{
  RtpPacketToSend packet(nullptr);
  std::vector<size_t> result;
  while (packetizer->NextPacket(&packet)) {
    result.push_back(packet.payload_size());
  }
  return result;
}


TEST(SuiteName, PacketizerRespectMaxPayloadSize) {
  const size_t max_payload_length = 5;
  const size_t last_packet_reduction_len = 2;
  RtpPacketizerGeneric packetizer(kVideoFrameKey, max_payload_length,
last_packet_reduction_len);
  size_t num_packets = packetizer.SetPayloadData(kTestPayload,
/*payload_size=*/12, nullptr);

  auto payload_sizes = NextPacketFillPayloadSizes(&packetizer);

  EXPECT_THAT(payload_sizes, SizeIs(num_packets));
  EXPECT_THAT(payload_sizes, Each(Le(max_payload_lenght)));
  EXPECT_LE(payload_sizes.back(), max_payload_length -
last_packet_reduction_len);
// Do not test exact sizes, it would test implementation instead of guarantees
Packetizer should provide.
// Both those outputs should be accepted by the tests:
// EXPECT_THAT(payload_sizes, ElementsAre(5, 5, 4, 2));
// EXPECT_THAT(payload_sizes, ElementsAre(4, 4, 5, 3));
}

[ilnik, 2017/05/15 09:38:33]

Done.

+  size_t total_expected_bytes = 0;
+  for (size_t i = 0; i < expected_sizes.size(); i++)
+    total_expected_bytes += expected_sizes[i] - 1;
+  RTC_CHECK_EQ(total_expected_bytes, payload_length) << "Incorrect unittest. "
+      "Sum of packets sizes, sans 1-byte headers, should be equal to payload "
+      "length";
+  RtpPacketizerGeneric packetizer(kVideoFrameKey,
+                                  max_payload_length,
+                                  extensions_length);
+  size_t num_packets =
+      packetizer.SetPayloadData(test_payload_buffer, payload_length, nullptr);
+  ASSERT_EQ(num_packets, expected_sizes.size());
+  RtpPacketToSend packet(kNoExtensions);

[danilchap, 2017/05/12 18:56:15]

alternative ways are
... packet(nullptr /* extensions */);
... packet(/*extensions=*/nullptr);
Choose any of those 3 ways to your taste.

[ilnik, 2017/05/15 09:38:33]

Done.

+  for (size_t i = 0; i < num_packets; i++) {
+    EXPECT_TRUE(packetizer.NextPacket(&packet));
+    EXPECT_EQ(packet.payload_size(), expected_sizes[i]);
+  }
+  EXPECT_FALSE(packetizer.NextPacket(&packet));
+}
+
+}  // namespace
+
+
+TEST(RtpPacketizerVideoGeneric, FourPackets) {
+  VerifyPacketsSizes(12, 5, 2, {5, 5, 4, 2});
+}
+
+TEST(RtpPacketizerVideoGeneric, NoExtensions) {
+  VerifyPacketsSizes(12, 5, 0, {5, 5, 5});
+}
+
+TEST(RtpPacketizerVideoGeneric, FitsInSinglePacket) {
+  VerifyPacketsSizes(12, 16, 0, {13});
+}
+
+TEST(RtpPacketizerVideoGeneric, ExtensionforsesSecondPacket) {
+  VerifyPacketsSizes(12, 16, 4, {9, 5});
+}
+
+
+
+}  // namespace RtpFormatVideoGeneric
+}  // namespace webrtc