[CrOS Tether] Create HostScanCache, which caches scan results and inserts them into the network sta…

chromeos/components/tether/host_scan_cache_unittest.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 "chromeos/components/tether/host_scan_cache.h"
+
+#include <memory>
+#include <unordered_map>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/ptr_util.h"
+#include "base/test/scoped_task_environment.h"
+#include "base/timer/mock_timer.h"
+#include "chromeos/components/tether/device_id_tether_network_guid_map.h"
+#include "chromeos/components/tether/fake_active_host.h"
+#include "chromeos/components/tether/fake_host_scan_cache.h"
+#include "chromeos/components/tether/mock_tether_host_response_recorder.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/network/network_state.h"
+#include "chromeos/network/network_state_handler.h"
+#include "chromeos/network/network_state_test.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using testing::NiceMock;
+using testing::Invoke;
+
+namespace chromeos {
+
+namespace tether {
+
+namespace {
+
+const char kTetherGuid0[] = "kTetherGuid0";
+const char kTetherGuid1[] = "kTetherGuid1";
+const char kTetherGuid2[] = "kTetherGuid2";
+const char kTetherGuid3[] = "kTetherGuid3";
+
+const char kTetherDeviceName0[] = "kDeviceName1";
+const char kTetherDeviceName1[] = "kDeviceName2";
+const char kTetherDeviceName2[] = "kDeviceName3";
+const char kTetherDeviceName3[] = "kDeviceName4";
+
+const char kTetherCarrier0[] = "kTetherCarrier0";
+const char kTetherCarrier1[] = "kTetherCarrier1";
+const char kTetherCarrier2[] = "kTetherCarrier2";
+const char kTetherCarrier3[] = "kTetherCarrier3";
+
+const int kTetherBatteryPercentage0 = 20;
+const int kTetherBatteryPercentage1 = 40;
+const int kTetherBatteryPercentage2 = 60;
+const int kTetherBatteryPercentage3 = 80;
+
+const int kTetherSignalStrength0 = 25;
+const int kTetherSignalStrength1 = 50;
+const int kTetherSignalStrength2 = 75;
+const int kTetherSignalStrength3 = 100;
+
+// MockTimer which invokes a callback in its destructor.
+class ExtendedMockTimer : public base::MockTimer {
+ public:
+  explicit ExtendedMockTimer(const base::Closure& destructor_callback)
+      : base::MockTimer(true /* retain_user_task */, false /* is_repeating */),
+        destructor_callback_(destructor_callback) {}
+
+  ~ExtendedMockTimer() override { destructor_callback_.Run(); }
+
+ private:
+  base::Closure destructor_callback_;
+};
+
+}  // namespace
+
+class HostScanCacheTest : public NetworkStateTest {
+ protected:
+  class MockTimerFactory : public HostScanCache::TimerFactory {

[stevenjb, 2017/05/01 18:26:11]

Mock has a specific meaning in chrome code. This is a fake.

[Kyle Horimoto, 2017/05/01 21:14:43]

Done.

+   public:
+    MockTimerFactory() {}
+    ~MockTimerFactory() {}
+
+    std::unordered_map<std::string, ExtendedMockTimer*>&
+    tether_network_guid_to_timer_map() {
+      return tether_network_guid_to_timer_map_;
+    }
+
+    // HostScanCache::TimerFactory:
+    std::unique_ptr<base::Timer> CreateOneShotTimer(
+        const std::string& tether_network_guid) override {
+      ExtendedMockTimer* mock_timer = new ExtendedMockTimer(
+          base::Bind(&MockTimerFactory::OnActiveTimerDestructor,
+                     base::Unretained(this), tether_network_guid));
+      tether_network_guid_to_timer_map_[tether_network_guid] = mock_timer;
+      return base::WrapUnique(mock_timer);
+    }
+
+   private:
+    void OnActiveTimerDestructor(const std::string& tether_network_guid) {
+      tether_network_guid_to_timer_map_.erase(
+          tether_network_guid_to_timer_map_.find(tether_network_guid));
+    }
+
+    std::unordered_map<std::string, ExtendedMockTimer*>
+        tether_network_guid_to_timer_map_;
+  };
+
+  HostScanCacheTest() {}
+
+  void SetUp() override {
+    DBusThreadManager::Initialize();
+    NetworkStateTest::SetUp();
+    network_state_handler()->SetTetherTechnologyState(
+        NetworkStateHandler::TECHNOLOGY_ENABLED);
+
+    mock_timer_factory_ = new MockTimerFactory();
+    fake_active_host_ = base::MakeUnique<FakeActiveHost>();
+    mock_tether_host_response_recorder_ =
+        base::MakeUnique<NiceMock<MockTetherHostResponseRecorder>>();
+    device_id_tether_network_guid_map_ =
+        base::MakeUnique<DeviceIdTetherNetworkGuidMap>();
+
+    ON_CALL(*mock_tether_host_response_recorder_,
+            GetPreviouslyConnectedHostIds())
+        .WillByDefault(
+            Invoke(this, &HostScanCacheTest::GetPreviouslyConnectedHostIds));
+
+    host_scan_cache_ = base::WrapUnique(new HostScanCache(
+        base::WrapUnique(mock_timer_factory_), network_state_handler(),
+        fake_active_host_.get(), mock_tether_host_response_recorder_.get(),
+        device_id_tether_network_guid_map_.get()));
+
+    // To track what is expected to be contained in the cache, maintain a
+    // FakeHostScanCache in memory and update it alongside |host_scan_cache_|.
+    // Use a std::vector to track which device IDs correspond to devices whose
+    // Tether networks' HasConnectedToHost fields are expected to be set.
+    expected_cache_ = base::MakeUnique<FakeHostScanCache>();

[stevenjb, 2017/05/01 18:26:11]

I am trying to review this but I am finding the tests extraordinarily confusing.

1. The added complexity of overriding HostScanCache::TimerFactory makes me sad.
I'm sure there is a better way to do that.

2. Having both a HostScanCache and a FakeHostScanCache in the tests hurts my
head. It really seems to me that HostScanCache should either have an observer
that the test can use to keep track of what is going on, or mechanisms to query
HostScanCache's internal state.

[Kyle Horimoto, 2017/05/01 21:14:43]

1. Addressed your comment. I added a set_tether_network_guid_for_next_timer()
function to the timer factory.

2. As discussed offline, I started adding an in-memory mapping for this, but it
essentially turned into the FakeHostScanCache implementation. I added a TODO to
clean this up at a later time.

+    has_connected_to_host_device_ids_.clear();
+  }
+
+  void TearDown() override {
+    ShutdownNetworkState();
+    NetworkStateTest::TearDown();
+    DBusThreadManager::Shutdown();
+  }
+
+  void FireTimer(const std::string& tether_network_guid) {
+    ExtendedMockTimer* timer =
+        mock_timer_factory_
+            ->tether_network_guid_to_timer_map()[tether_network_guid];
+    ASSERT_TRUE(timer);
+    timer->Fire();
+
+    // If the device whose correlated timer has fired is not the active host, it
+    // is expected to be removed from the cache.
+    EXPECT_EQ(fake_active_host_->GetTetherNetworkGuid(),
+              expected_cache_->active_host_tether_network_guid());
+    if (fake_active_host_->GetTetherNetworkGuid() != tether_network_guid) {
+      expected_cache_->RemoveHostScanResult(tether_network_guid);
+    }
+  }
+
+  std::vector<std::string> GetPreviouslyConnectedHostIds() const {
+    return has_connected_to_host_device_ids_;
+  }
+
+  void SetActiveHost(const std::string& tether_network_guid) {
+    fake_active_host_->SetActiveHostConnected(
+        device_id_tether_network_guid_map_->GetDeviceIdForTetherNetworkGuid(
+            tether_network_guid),
+        tether_network_guid, "wifiNetworkGuid");
+    expected_cache_->set_active_host_tether_network_guid(tether_network_guid);
+  }
+
+  void SetHasConnectedToHost(const std::string& tether_network_guid) {
+    has_connected_to_host_device_ids_.push_back(
+        device_id_tether_network_guid_map_->GetDeviceIdForTetherNetworkGuid(
+            tether_network_guid));
+    mock_tether_host_response_recorder_
+        ->NotifyPreviouslyConnectedHostIdsChanged();
+  }
+
+  // Sets host scan results in the cache for the device at index |index|. Index
+  // can be from 0 to 3 and corresponds to the index of the constants declared
+  // at the top of this test file.
+  void SetCacheScanResultForDeviceIndex(int32_t index) {
+    // There are 4 sets of test constants.
+    ASSERT_TRUE(index >= 0 && index <= 3);
+
+    std::string tether_network_guid;
+    std::string device_name;
+    std::string carrier;
+    int battery_percentage;
+    int signal_strength;
+
+    switch (index) {
+      case 0:
+        tether_network_guid = kTetherGuid0;
+        device_name = kTetherDeviceName0;
+        carrier = kTetherCarrier0;
+        battery_percentage = kTetherBatteryPercentage0;
+        signal_strength = kTetherSignalStrength0;
+        break;
+      case 1:
+        tether_network_guid = kTetherGuid1;
+        device_name = kTetherDeviceName1;
+        carrier = kTetherCarrier1;
+        battery_percentage = kTetherBatteryPercentage1;
+        signal_strength = kTetherSignalStrength1;
+        break;
+      case 2:
+        tether_network_guid = kTetherGuid2;
+        device_name = kTetherDeviceName2;
+        carrier = kTetherCarrier2;
+        battery_percentage = kTetherBatteryPercentage2;
+        signal_strength = kTetherSignalStrength2;
+        break;
+      case 3:
+        tether_network_guid = kTetherGuid3;
+        device_name = kTetherDeviceName3;
+        carrier = kTetherCarrier3;
+        battery_percentage = kTetherBatteryPercentage3;
+        signal_strength = kTetherSignalStrength3;
+        break;
+      default:
+        NOTREACHED();
+        // Set values for |battery_percentage| and |signal_strength| here to
+        // prevent a compiler warning which says that they may be unset at this
+        // point.
+        battery_percentage = 0;
+        signal_strength = 0;
+        break;
+    }
+
+    SetHostScanResult(tether_network_guid, device_name, carrier,
+                      battery_percentage, signal_strength);
+  }
+
+  void SetHostScanResult(const std::string& tether_network_guid,
+                         const std::string& device_name,
+                         const std::string& carrier,
+                         int battery_percentage,
+                         int signal_strength) {
+    host_scan_cache_->SetHostScanResult(tether_network_guid, device_name,
+                                        carrier, battery_percentage,
+                                        signal_strength);
+    expected_cache_->SetHostScanResult(tether_network_guid, device_name,
+                                       carrier, battery_percentage,
+                                       signal_strength);
+  }
+
+  void RemoveHostScanResult(const std::string& tether_network_guid) {
+    host_scan_cache_->RemoveHostScanResult(tether_network_guid);
+    expected_cache_->RemoveHostScanResult(tether_network_guid);
+  }
+
+  void ClearCacheExceptForActiveHost() {
+    host_scan_cache_->ClearCacheExceptForActiveHost();
+    expected_cache_->ClearCacheExceptForActiveHost();
+  }
+
+  bool HasConnectedToHost(const std::string& tether_network_guid) {
+    auto it =
+        std::find(has_connected_to_host_device_ids_.begin(),
+                  has_connected_to_host_device_ids_.end(), tether_network_guid);
+    return it != has_connected_to_host_device_ids_.end();
+  }
+
+  // Verifies that the information present in |expected_cache_| and
+  // |has_connected_to_host_device_ids_| mirrors what |host_scan_cache_| has set
+  // in NetworkStateHandler.
+  void VerifyCacheMatchesNetworkStack() {
+    for (auto& it : expected_cache_->cache()) {
+      const std::string tether_network_guid = it.first;
+      const FakeHostScanCache::CacheEntry cache_entry = it.second;
+
+      // Ensure that each entry in |expected_cache_| matches the
+      // corresponding entry in NetworkStateHandler.
+      const NetworkState* tether_network_state =
+          network_state_handler()->GetNetworkStateFromGuid(tether_network_guid);
+      ASSERT_TRUE(tether_network_state);
+      EXPECT_EQ(cache_entry.device_name, tether_network_state->name());
+      EXPECT_EQ(cache_entry.carrier, tether_network_state->carrier());
+      EXPECT_EQ(cache_entry.battery_percentage,
+                tether_network_state->battery_percentage());
+      EXPECT_EQ(cache_entry.signal_strength,
+                tether_network_state->signal_strength());
+      EXPECT_EQ(HasConnectedToHost(tether_network_guid),
+                tether_network_state->tether_has_connected_to_host());
+
+      // Ensure that each entry has an actively-running Timer.
+      auto timer_map_it =
+          mock_timer_factory_->tether_network_guid_to_timer_map().begin();
+      EXPECT_NE(timer_map_it,
+                mock_timer_factory_->tether_network_guid_to_timer_map().end());
+      EXPECT_TRUE(timer_map_it->second->IsRunning());
+    }
+  }
+
+  const base::test::ScopedTaskEnvironment scoped_task_environment_;
+
+  MockTimerFactory* mock_timer_factory_;
+  std::unique_ptr<FakeActiveHost> fake_active_host_;
+  std::unique_ptr<NiceMock<MockTetherHostResponseRecorder>>
+      mock_tether_host_response_recorder_;
+  // TODO(hansberry): Use a fake for this when a real mapping scheme is created.
+  std::unique_ptr<DeviceIdTetherNetworkGuidMap>
+      device_id_tether_network_guid_map_;
+
+  std::vector<std::string> has_connected_to_host_device_ids_;
+  std::unique_ptr<FakeHostScanCache> expected_cache_;
+
+  std::unique_ptr<HostScanCache> host_scan_cache_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HostScanCacheTest);
+};
+
+TEST_F(HostScanCacheTest, TestSetScanResultsAndLetThemExpire) {
+  SetCacheScanResultForDeviceIndex(0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(1);
+  EXPECT_EQ(2u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(2);
+  EXPECT_EQ(3u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(3);
+  EXPECT_EQ(4u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  FireTimer(kTetherGuid0);
+  EXPECT_EQ(3u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  FireTimer(kTetherGuid1);
+  EXPECT_EQ(2u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  FireTimer(kTetherGuid2);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  FireTimer(kTetherGuid3);
+  EXPECT_TRUE(expected_cache_->empty());
+  VerifyCacheMatchesNetworkStack();
+}
+
+TEST_F(HostScanCacheTest, TestSetScanResultThenUpdateAndRemove) {
+  SetCacheScanResultForDeviceIndex(0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Change the fields for tether network with GUID |kTetherGuid0| to the
+  // fields corresponding to |kTetherGuid1|.
+  SetHostScanResult(kTetherGuid0, kTetherDeviceName0, kTetherCarrier1,
+                    kTetherBatteryPercentage1, kTetherSignalStrength1);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Now, remove that result.
+  RemoveHostScanResult(kTetherGuid0);
+  EXPECT_TRUE(expected_cache_->empty());
+  VerifyCacheMatchesNetworkStack();
+}
+
+TEST_F(HostScanCacheTest, TestSetScanResult_SetActiveHost_ThenClear) {
+  SetCacheScanResultForDeviceIndex(0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(1);
+  EXPECT_EQ(2u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(2);
+  EXPECT_EQ(3u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Now, set the active host to be the device 0.
+  SetActiveHost(kTetherGuid0);
+
+  // Clear the cache except for the active host.
+  ClearCacheExceptForActiveHost();
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Attempt to remove the active host. This operation should fail since
+  // removing the active host from the cache is not allowed.
+  RemoveHostScanResult(kTetherGuid0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Fire the timer for the active host. Likewise, this should not result in the
+  // cache entry being removed.
+  FireTimer(kTetherGuid0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Now, unset the active host.
+  SetActiveHost("");
+
+  // Removing the device should now succeed.
+  RemoveHostScanResult(kTetherGuid0);
+  EXPECT_TRUE(expected_cache_->empty());
+  VerifyCacheMatchesNetworkStack();
+}
+
+TEST_F(HostScanCacheTest, TestHasConnectedToHost) {
+  // Before the test starts, set device 0 as having already connected.
+  SetHasConnectedToHost(kTetherGuid0);
+
+  SetCacheScanResultForDeviceIndex(0);
+  EXPECT_EQ(1u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  SetCacheScanResultForDeviceIndex(1);
+  EXPECT_EQ(2u, expected_cache_->size());
+  VerifyCacheMatchesNetworkStack();
+
+  // Simulate a connection to device 1.
+  SetActiveHost(kTetherGuid1);
+  SetHasConnectedToHost(kTetherGuid1);
+  VerifyCacheMatchesNetworkStack();
+}
+
+}  // namespace tether
+
+}  // namespace chromeos