Make RTCStatsReport::ToString() return JSON-parseable string.

webrtc/stats/rtcstats_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.
  */
 
 #include "webrtc/api/stats/rtcstats.h"
 
 #include <cstring>
 
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/gunit.h"
+#include "webrtc/rtc_base/json.h"
 #include "webrtc/stats/test/rtcteststats.h"
 
 namespace webrtc {
 
 class RTCChildStats : public RTCStats {
  public:
   WEBRTC_RTCSTATS_DECL();
 
   RTCChildStats(const std::string& id, int64_t timestamp_us)
       : RTCStats(id, timestamp_us),
@@ skipping 162 matching lines @@
     sum += *member->cast_to<const RTCStatsMember<int32_t>>();
   }
   EXPECT_EQ(sum, static_cast<int32_t>(3));
 
   std::unique_ptr<RTCStats> copy_ptr = stats.copy();
   const RTCGrandChildStats& copy = copy_ptr->cast_to<RTCGrandChildStats>();
   EXPECT_EQ(*copy.child_int, *stats.child_int);
   EXPECT_EQ(*copy.grandchild_int, *stats.grandchild_int);
 }
 
+TEST(RTCStatsTest, RTCStatsPrintsValidJson) {
+  std::string id = "statsId";
+  int timestamp = 42;
+  bool m_bool = true;
+  int m_int32 = 123;
+  double m_double = 123.0;
+  std::string m_string = "123";
+
+  std::vector<bool> sequence_bool;
+  std::vector<int32_t> sequence_int32;
+  sequence_int32.push_back(static_cast<int32_t>(1));
+  std::vector<double> sequence_double;
+  sequence_double.push_back(2.0);
+  sequence_double.push_back(3.0);
+  std::vector<std::string> sequence_string;
+  sequence_string.push_back(std::string("four"));
+
+  RTCTestStats stats(id, timestamp);
+  stats.m_bool = m_bool;
+  stats.m_int32 = m_int32;
+  stats.m_double = m_double;
+  stats.m_string = m_string;
+  stats.m_sequence_bool = sequence_bool;
+  stats.m_sequence_int32 = sequence_int32;
+  stats.m_sequence_double = sequence_double;
+  stats.m_sequence_string = sequence_string;

[hbos, 2017/07/25 12:29:21]

Hmm, will this be a problem for you?
https://stackoverflow.com/questions/16809932/does-libjson-support-64-bit-int-...

It seems our json library has the types you test here, but not the
uint64_t/int64_t values:
https://cs.chromium.org/chromium/src/third_party/jsoncpp/source/include/json/...

When we surface stats to JavaScript of course we're limited by JavaScript
precision as well, and we static_cast all integer types to double since that's
how numbers are stored in the resulting objects:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/peerco...

Converting 64-bit to double may yield loss of precision. This is fine, but not
necessary in C++ land. But if JSON is we need to static_cast before ToJson.

Can you add large 64-bit values to the unittest. See if JSON can parse it large
64-bit values as double, otherwise output the 64-bit values as lossy doubles.
That might be the safest. Outputting all as double will yield the same values as
the JavaScript view of the stats.

+
+  Json::Value json_output;
+  EXPECT_TRUE(Json::Reader().parse(stats.ToString(), json_output));
+
+  EXPECT_TRUE(rtc::GetStringFromJsonObject(json_output, "id", &id));
+  EXPECT_TRUE(rtc::GetIntFromJsonObject(json_output, "timestamp", &timestamp));
+  EXPECT_TRUE(rtc::GetBoolFromJsonObject(json_output, "mBool", &m_bool));
+  EXPECT_TRUE(rtc::GetIntFromJsonObject(json_output, "mInt32", &m_int32));
+  EXPECT_TRUE(rtc::GetStringFromJsonObject(json_output, "mString", &m_string));

[hbos, 2017/07/25 12:29:21]

nit: you skipped mDouble

+
+  Json::Value json_array;
+
+  EXPECT_TRUE(
+      rtc::GetValueFromJsonObject(json_output, "mSequenceBool", &json_array));
+  EXPECT_TRUE(rtc::JsonArrayToBoolVector(json_array, &sequence_bool));
+
+  EXPECT_TRUE(
+      rtc::GetValueFromJsonObject(json_output, "mSequenceInt32", &json_array));
+  EXPECT_TRUE(rtc::JsonArrayToIntVector(json_array, &sequence_int32));
+
+  EXPECT_TRUE(
+      rtc::GetValueFromJsonObject(json_output, "mSequenceDouble", &json_array));
+  EXPECT_TRUE(rtc::JsonArrayToDoubleVector(json_array, &sequence_double));
+
+  EXPECT_TRUE(
+      rtc::GetValueFromJsonObject(json_output, "mSequenceString", &json_array));
+  EXPECT_TRUE(rtc::JsonArrayToStringVector(json_array, &sequence_string));
+
+  EXPECT_EQ(id, stats.id());
+  EXPECT_EQ(timestamp, stats.timestamp_us());
+  EXPECT_EQ(m_bool, *stats.m_bool);
+  EXPECT_EQ(m_int32, *stats.m_int32);
+  EXPECT_EQ(m_string, *stats.m_string);
+  EXPECT_EQ(sequence_bool, *stats.m_sequence_bool);
+  EXPECT_EQ(sequence_int32, *stats.m_sequence_int32);
+  EXPECT_EQ(sequence_double, *stats.m_sequence_double);
+  EXPECT_EQ(sequence_string, *stats.m_sequence_string);
+
+  // stats.m_int64 is not defined, so "mInt64" is not part of the generated json
+  // object.
+  int m_int64;
+  EXPECT_FALSE(stats.m_int64.is_defined());
+  EXPECT_FALSE(rtc::GetIntFromJsonObject(json_output, "mInt64", &m_int64));

[hbos, 2017/07/25 12:29:21]

This is good. Keep at least one member undefined to EXPECT it to be missing,
even if the 64-bit members are used based on previous comment.

+}
+
 // Death tests.
 // Disabled on Android because death tests misbehave on Android, see
 // base/test/gtest_util.h.
 #if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
 
 TEST(RTCStatsDeathTest, ValueOfUndefinedMember) {
   RTCTestStats stats("testId", 0.0);
   EXPECT_FALSE(stats.m_int32.is_defined());
   EXPECT_DEATH(*stats.m_int32, "");
 }
 
 TEST(RTCStatsDeathTest, InvalidCasting) {
   RTCGrandChildStats stats("grandchild", 0.0);
   EXPECT_DEATH(stats.cast_to<RTCChildStats>(), "");
 }
 
 #endif  // RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
 
 }  // namespace webrtc