chromium/third_party/openscreen/src/cast/streaming/impl/bandwidth_estimator_unittest.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cast/streaming/impl/bandwidth_estimator.h"

#include <chrono>
#include <limits>
#include <random>

#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "platform/api/time.h"
#include "util/chrono_helpers.h"

namespace openscreen::cast {
namespace {

operator<<;

// BandwidthEstimator configuration common to all tests.
constexpr int kMaxPacketsPerTimeslice = …;
constexpr Clock::duration kTimesliceDuration = …;
constexpr int kTimeslicesPerSecond = …;

// Use a fake, fixed start time.
constexpr Clock::time_point kStartTime = …;

// Range of "fuzz" to add to timestamps in BandwidthEstimatorTest::AddFuzz().
constexpr Clock::duration kMaxFuzzOffset = …;
constexpr int kFuzzLowerBoundClockTicks = …;
constexpr int kFuzzUpperBoundClockTicks = …;

class BandwidthEstimatorTest : public testing::Test { … };

// Tests that, without any data, there won't be any estimates.
TEST_F(BandwidthEstimatorTest, DoesNotEstimateWithoutAnyInput) { … }

// Tests the case where packets are being sent, but the Receiver hasn't provided
// feedback (e.g., due to a network blackout).
TEST_F(BandwidthEstimatorTest, DoesNotEstimateWithoutFeedback) { … }

// Tests the case where packets are being sent, and a connection to the Receiver
// has been confirmed (because RTCP packets are coming in), but the Receiver has
// not successfully received anything.
TEST_F(BandwidthEstimatorTest, DoesNotEstimateIfNothingSuccessfullyReceived) { … }

// Tests that, when the Receiver successfully receives the payload bytes at a
// fixed rate, the network bandwidth estimates are based on the amount of time
// the Sender spent transmitting.
TEST_F(BandwidthEstimatorTest, EstimatesAtVariousBurstSaturations) { … }

// Tests that magnitude of the network round trip times, as well as random
// variance in packet arrival times, do not have a significant effect on the
// bandwidth estimates.
TEST_F(BandwidthEstimatorTest, EstimatesIndependentOfFeedbackDelays) { … }

// Tests that both the history tracking internal to BandwidthEstimator, as well
// as its computation of the bandwidth estimate, are both resistant to possible
// integer overflow cases. The internal implementation always clamps to the
// valid range of int.
TEST_F(BandwidthEstimatorTest, ClampsEstimateToMaxInt) { … }

}  // namespace
}  // namespace openscreen::cast