ui/views/controls/label_perftest.cc

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/controls/label.h"

#include "base/strings/utf_string_conversions.h"
#include "base/timer/lap_timer.h"
#include "testing/perf/perf_result_reporter.h"
#include "ui/views/test/views_test_base.h"

namespace views {

using LabelPerfTest = ViewsTestBase;

// Test the number of text size measurements that can be made made per second.
// This should surface any performance regressions in underlying text layout
// system, e.g., failure to cache font structures.
TEST_F(LabelPerfTest, GetPreferredSize) {
  Label label;

  // Alternate between two strings to ensure caches are cleared.
  base::string16 string1 = base::ASCIIToUTF16("boring ascii string");
  base::string16 string2 = base::ASCIIToUTF16("another uninteresting sequence");

  constexpr int kLaps = 5000;  // Aim to run in under 3 seconds.
  constexpr int kWarmupLaps = 5;

  // The time limit is unused. Use kLaps for the check interval so the time is
  // only measured once.
  base::LapTimer timer(kWarmupLaps, base::TimeDelta(), kLaps);
  for (int i = 0; i < kLaps + kWarmupLaps; ++i) {
    label.SetText(i % 2 == 0 ? string1 : string2);
    label.GetPreferredSize();
    timer.NextLap();
  }
  perf_test::PerfResultReporter reporter("LabelPerfTest", "GetPreferredSize");
  reporter.RegisterImportantMetric("", "runs/s");
  reporter.AddResult("", timer.LapsPerSecond());
}

}  // namespace views