metrics: Add leak detector controller in Chrome OS metrics system

components/metrics/leak_detector/leak_detector_unittest.cc

+// Copyright 2016 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 "components/metrics/leak_detector/leak_detector.h"
+
+#include <set>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace metrics {
+
+namespace {
+
+// Observer class that receives leak reports and stores them in |reports_|.
+// Only one copy of each unique report will be stored.
+class TestObserver : public LeakDetector::LeakDetector::Observer {
+ public:
+  TestObserver() {}
+
+  void OnLeakFound(const LeakDetector::LeakReport& report) override {
+    reports_.insert(report);
+  }
+
+  const std::set<LeakDetector::LeakReport>& reports() const { return reports_; }
+
+ private:
+  std::set<LeakDetector::LeakReport> reports_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestObserver);
+};
+
+}  // namespace
+
+class LeakDetectorTest : public ::testing::Test {
+ public:
+  LeakDetectorTest() {}
+
+  void SetUp() override { detector_.reset(new LeakDetector); }

[Alexei Svitkine (slow), 2016/02/10 20:16:58]

You can just put this in the ctor and avoid having SetUp() and TearDown()
methods.

A new instance of the Test object will be instantiated for each test. In fact,
you don't need to even make it a scoped_ptr - can just be a direct member.

[Simon Que, 2016/02/11 01:45:38]

I actually call "detector_.reset()" in the second unit test.

In a future unit test, I will be instantiating the class with non-default
parameters. Making it a direct member doesn't work.

However, I can get rid of SetUp() and TearDown(). Note that in a future CL, I
plan to check the allocator hooks before and after each test, so I might still
need to have those functions (see http://crrev.com/1665553002/).

+
+  void TearDown() override { detector_.reset(); }
+
+ protected:
+  scoped_ptr<LeakDetector> detector_;
+
+ protected:

[Alexei Svitkine (slow), 2016/02/10 20:16:58]

private:

[Simon Que, 2016/02/11 01:45:38]

Done.

+  DISALLOW_COPY_AND_ASSIGN(LeakDetectorTest);
+};
+
+TEST_F(LeakDetectorTest, AddAndRemoveObservers) {
+  TestObserver obs1, obs2, obs3;
+
+  // There are no registered observers at first. Make sure RemoveObserver()
+  // returns false in this case.
+  EXPECT_FALSE(detector_->RemoveObserver(&obs1));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs2));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs3));
+
+  // Add observer and then remove it.
+  EXPECT_TRUE(detector_->AddObserver(&obs1));
+  EXPECT_TRUE(detector_->RemoveObserver(&obs1));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs1));
+
+  // Add all three observers at once, then remove them.
+  EXPECT_TRUE(detector_->AddObserver(&obs1));
+  EXPECT_TRUE(detector_->AddObserver(&obs2));
+  EXPECT_TRUE(detector_->AddObserver(&obs3));
+
+  EXPECT_TRUE(detector_->RemoveObserver(&obs1));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs1));
+  EXPECT_TRUE(detector_->RemoveObserver(&obs2));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs2));
+  EXPECT_TRUE(detector_->RemoveObserver(&obs3));
+  EXPECT_FALSE(detector_->RemoveObserver(&obs3));
+}
+
+TEST_F(LeakDetectorTest, NotifyObservers) {
+  // Generate two sets of leak reports.
+  std::vector<LeakDetector::LeakReport> reports1(3);
+  reports1[0].alloc_size_bytes = 8;
+  reports1[0].call_stack = {1, 2, 3, 4};
+  reports1[1].alloc_size_bytes = 16;
+  reports1[1].call_stack = {5, 6, 7, 8};
+  reports1[2].alloc_size_bytes = 24;
+  reports1[2].call_stack = {9, 10, 11, 12};
+
+  std::vector<LeakDetector::LeakReport> reports2(3);
+  reports2[0].alloc_size_bytes = 32;
+  reports2[0].call_stack = {1, 2, 4, 8};
+  reports2[1].alloc_size_bytes = 40;
+  reports2[1].call_stack = {16, 32, 64, 128};
+  reports2[2].alloc_size_bytes = 48;
+  reports2[2].call_stack = {256, 512, 1024, 2048};
+
+  // Register three observers;
+  TestObserver obs1, obs2, obs3;
+  ASSERT_TRUE(detector_->AddObserver(&obs1));
+  ASSERT_TRUE(detector_->AddObserver(&obs2));
+  ASSERT_TRUE(detector_->AddObserver(&obs3));
+
+  // Pass both sets of reports to the leak detector.
+  detector_->NotifyObservers(reports1);
+  detector_->NotifyObservers(reports2);
+
+  // Shut down the leak detector before checking the reports, so that the
+  // stored reports can be examined without new reports being generated.
+  detector_.reset();
+
+  // Check that all three observers got both sets of reports, passed in
+  // separately.
+  for (const TestObserver* obs : {&obs1, &obs2, &obs3}) {
+    EXPECT_EQ(6U, obs->reports().size());
+    for (const auto& report : {reports1[0], reports1[1], reports1[2],
+                               reports2[0], reports2[1], reports2[2]}) {
+      EXPECT_TRUE(obs->reports().find(report) != obs->reports().end());
+    }
+  }
+}
+
+}  // namespace metrics