[sensors](CrOS/Linux) Implement Sensor device manager for sensors

device/generic_sensor/platform_sensor_and_provider_unittest_linux.cc

Index: device/generic_sensor/platform_sensor_and_provider_unittest_linux.cc
diff --git a/device/generic_sensor/platform_sensor_and_provider_unittest_linux.cc b/device/generic_sensor/platform_sensor_and_provider_unittest_linux.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0cb9fc4d0ea0e660b51bbb0df01f20915aa7604c
--- /dev/null
+++ b/device/generic_sensor/platform_sensor_and_provider_unittest_linux.cc
@@ -0,0 +1,661 @@
+// 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 "base/files/file_util.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+
+#include "device/generic_sensor/generic_sensor_consts.h"
+#include "device/generic_sensor/linux/sensor_data_linux.h"
+#include "device/generic_sensor/platform_sensor_manager_linux.h"
+#include "device/generic_sensor/platform_sensor_provider_linux.h"
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::_;
+using ::testing::Invoke;
+using ::testing::IsNull;
+using ::testing::NiceMock;
+using ::testing::NotNull;
+using ::testing::Return;
+
+namespace device {
+
+namespace {
+
+using mojom::SensorType;
+
+// Zero value can mean whether value is not being not used or zero value.
+constexpr double kZero = 0.0;
+
+constexpr double kAccelerometerFrequencyValue = 10.0;
+constexpr double kAccelerometerOffsetValue = 1.0;
+constexpr double kAccelerometerScalingValue = 0.009806;
+
+constexpr double kGyroscopeFrequencyValue = 6.0;
+constexpr double kGyroscopeOffsetValue = 2.0;
+constexpr double kGyroscopeScalingValue = 0.000017;
+
+constexpr double kMagnetometerFrequencyValue = 7.0;
+constexpr double kMagnetometerOffsetValue = 3.0;
+constexpr double kMagnetometerScalingValue = 0.000001;
+
+void DeleteFile(const base::FilePath& file) {
+  EXPECT_TRUE(base::DeleteFile(file, true));
+}
+
+void WriteValueToFile(const base::FilePath& path, double value) {
+  const std::string str = base::DoubleToString(value);
+  int bytes_written = base::WriteFile(path, str.data(), str.size());
+  EXPECT_EQ(static_cast<size_t>(bytes_written), str.size());
+}
+
+std::string ReadValueFromFile(const base::FilePath& path,
+                              const std::string& file) {
+  base::FilePath file_path = base::FilePath(path).Append(file);
+  std::string new_read_value;
+  if (!base::ReadFileToString(file_path, &new_read_value))
+    return std::string();
+  return new_read_value;
+}
+
+}  // namespace
+
+// Mock for SensorDeviceService that SensorDeviceManager owns.
+// This mock is used to emulate udev events and send found sensor devices
+// to SensorDeviceManager.
+class MockSensorDeviceManager : public SensorDeviceManager {
+ public:
+  MockSensorDeviceManager() = default;
+  ~MockSensorDeviceManager() override {}
+
+  MOCK_METHOD1(GetUdevDeviceGetSubsystem, std::string(udev_device*));
+  MOCK_METHOD1(GetUdevDeviceGetSyspath, std::string(udev_device*));
+  MOCK_METHOD1(GetUdevDeviceGetDevnode, std::string(udev_device* dev));
+  MOCK_METHOD2(GetUdevDeviceGetSysattrValue,
+               std::string(udev_device*, const std::string&));
+  MOCK_METHOD1(Start, void(Delegate*));
+
+  void InitializeService(Delegate* delegate) { delegate_ = delegate; }
+
+  void EnumerationReady() {
+    bool success = task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&SensorDeviceManager::Delegate::OnEnumerationReady,
+                   base::Unretained(delegate_)));
+    ASSERT_TRUE(success);
+  }
+
+  void DeviceAdded(udev_device* dev) {
+    SensorDeviceManager::OnDeviceAdded(dev);
+  }
+
+  void DeviceRemoved(udev_device* dev) {
+    SensorDeviceManager::OnDeviceRemoved(dev);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MockSensorDeviceManager);
+};
+
+// Mock for PlatformSensor's client interface that is used to deliver
+// error and data changes notifications.
+class MockPlatformSensorClient : public PlatformSensor::Client {
+ public:
+  MockPlatformSensorClient() = default;
+  explicit MockPlatformSensorClient(scoped_refptr<PlatformSensor> sensor)
+      : sensor_(sensor) {
+    if (sensor_)
+      sensor_->AddClient(this);
+
+    ON_CALL(*this, IsNotificationSuspended()).WillByDefault(Return(false));
+  }
+
+  ~MockPlatformSensorClient() override {
+    if (sensor_)
+      sensor_->RemoveClient(this);
+  }
+
+  // PlatformSensor::Client interface.
+  MOCK_METHOD0(OnSensorReadingChanged, void());
+  MOCK_METHOD0(OnSensorError, void());
+  MOCK_METHOD0(IsNotificationSuspended, bool());
+
+ private:
+  scoped_refptr<PlatformSensor> sensor_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockPlatformSensorClient);
+};
+
+class PlatformSensorAndProviderLinuxTest : public ::testing::Test {
+ public:
+  void SetUp() override {
+    provider_ = PlatformSensorProviderLinux::GetInstance();
+    provider_->SetFileTaskRunnerForTesting(message_loop_.task_runner());
+
+    auto manager = base::MakeUnique<NiceMock<MockSensorDeviceManager>>();
+    manager_ = manager.get();
+    provider_->SetSensorDeviceManagerForTesting(std::move(manager));
+
+    ASSERT_TRUE(sensors_dir_.CreateUniqueTempDir());
+  }
+
+  void TearDown() override {
+    provider_->SetSensorDeviceManagerForTesting(nullptr);
+    ASSERT_TRUE(sensors_dir_.Delete());
+    base::RunLoop().RunUntilIdle();
+  }
+
+ protected:
+  void SensorsCreated(scoped_refptr<PlatformSensor> sensor) {
+    platform_sensor_vector_.push_back(sensor);
+  }
+
+  void SensorCreated(scoped_refptr<PlatformSensor> sensor) {
+    platform_sensor_ = sensor;
+    run_loop_->Quit();
+  }
+
+  // Sensor creation is asynchronous, therefore inner loop is used to wait for
+  // PlatformSensorProvider::CreateSensorCallback completion.
+  scoped_refptr<PlatformSensor> CreateSensor(mojom::SensorType type) {
+    run_loop_ = base::MakeUnique<base::RunLoop>();
+    provider_->CreateSensor(
+        type, base::Bind(&PlatformSensorAndProviderLinuxTest::SensorCreated,
+                         base::Unretained(this)));
+    run_loop_->Run();
+    scoped_refptr<PlatformSensor> sensor;
+    sensor.swap(platform_sensor_);
+    run_loop_ = nullptr;
+    return sensor;
+  }
+
+  // Creates sensor files according to SensorPathsLinux.
+  // Existence of sensor read files mean existence of a sensor.
+  void InitializeSupportedSensor(SensorType type,
+                                 double frequency,
+                                 double offset,
+                                 double scaling,
+                                 double values[3]) {
+    SensorPathsLinux data;
+    EXPECT_TRUE(InitSensorData(type, &data));
+
+    base::FilePath sensor_dir = sensors_dir_.GetPath();
+    if (!data.sensor_scale_name.empty()) {
+      base::FilePath sensor_scale_file =
+          base::FilePath(sensor_dir).Append(data.sensor_scale_name);
+      WriteValueToFile(sensor_scale_file, scaling);
+    }
+
+    if (!data.sensor_offset_file_name.empty()) {
+      base::FilePath sensor_offset_file =
+          base::FilePath(sensor_dir).Append(data.sensor_offset_file_name);
+      WriteValueToFile(sensor_offset_file, offset);
+    }
+
+    if (!data.sensor_frequency_file_name.empty()) {
+      base::FilePath sensor_frequency_file =
+          base::FilePath(sensor_dir).Append(data.sensor_frequency_file_name);
+      WriteValueToFile(sensor_frequency_file, frequency);
+    }
+
+    uint32_t i = 0;
+    for (const auto& file_names : data.sensor_file_names) {
+      for (const auto& name : file_names) {
+        base::FilePath sensor_file = base::FilePath(sensor_dir).Append(name);
+        WriteValueToFile(sensor_file, values[i++]);
+        break;
+      }
+    }
+  }
+
+  // Initializes mock udev methods that emulate system methods by
+  // just reading values from files, which SensorDeviceService has specified
+  // calling udev methods.
+  void InitializeMockUdevMethods(const base::FilePath& sensor_dir) {
+    ON_CALL(*manager_, GetUdevDeviceGetSubsystem(IsNull()))
+        .WillByDefault(Invoke([this](udev_device* dev) { return "iio"; }));
+
+    ON_CALL(*manager_, GetUdevDeviceGetSyspath(IsNull()))
+        .WillByDefault(Invoke(
+            [sensor_dir](udev_device* dev) { return sensor_dir.value(); }));
+
+    ON_CALL(*manager_, GetUdevDeviceGetDevnode(IsNull()))
+        .WillByDefault(
+            Invoke([this](udev_device* dev) { return "/dev/test"; }));
+
+    ON_CALL(*manager_, GetUdevDeviceGetSysattrValue(IsNull(), _))
+        .WillByDefault(Invoke(
+            [sensor_dir](udev_device* dev, const std::string& attribute) {
+              return ReadValueFromFile(sensor_dir, attribute);
+            }));
+  }
+
+  // Emulates device enumerations and initial udev events. Once all
+  // devices are added, tells manager its ready.
+  void SetServiceStart() {
+    EXPECT_CALL(*manager_, Start(NotNull()))
+        .WillOnce(Invoke([this](SensorDeviceManager::Delegate* delegate) {
+          manager_->InitializeService(delegate);
+          udev_device* dev = nullptr;
+          manager_->DeviceAdded(dev /* not used */);
+          manager_->EnumerationReady();
+        }));
+  }
+
+  // Waits before OnSensorReadingChanged is called.
+  void WaitOnSensorReadingChangedEvent(MockPlatformSensorClient* client) {
+    run_loop_ = base::MakeUnique<base::RunLoop>();
+    EXPECT_CALL(*client, OnSensorReadingChanged()).WillOnce(Invoke([this]() {
+      run_loop_->Quit();
+    }));
+    run_loop_->Run();
+    run_loop_ = nullptr;
+  }
+
+  // Waits before OnSensorError is called.
+  void WaitOnSensorErrorEvent(MockPlatformSensorClient* client) {
+    run_loop_ = base::MakeUnique<base::RunLoop>();
+    EXPECT_CALL(*client, OnSensorError()).WillOnce(Invoke([this]() {
+      run_loop_->Quit();
+    }));
+    run_loop_->Run();
+    run_loop_ = nullptr;
+  }
+
+  // Generates a "remove device" event by removed sensors' directory and
+  // notifies the mock service about "removed" event.
+  void GenerateDeviceRemovedEvent(const base::FilePath& sensor_dir) {
+    udev_device* dev = nullptr;
+    DeleteFile(sensor_dir);
+    bool success = base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&MockSensorDeviceManager::DeviceRemoved,
+                              base::Unretained(manager_), dev /* not used */));
+    ASSERT_TRUE(success);
+  }
+
+  MockSensorDeviceManager* manager_;
+  scoped_refptr<PlatformSensor> platform_sensor_;
+  std::vector<scoped_refptr<PlatformSensor>> platform_sensor_vector_;
+  base::MessageLoop message_loop_;
+  std::unique_ptr<base::RunLoop> run_loop_;
+  PlatformSensorProviderLinux* provider_;
+  // Holds base dir where a sensor dir is located.
+  base::ScopedTempDir sensors_dir_;
+};
+
+// Tests sensor is not returned if not implemented.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorIsNotImplemented) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  SetServiceStart();
+  EXPECT_FALSE(CreateSensor(SensorType::PROXIMITY));
+}
+
+// Tests sensor is not returned if not supported by hardware.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorIsNotSupported) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  SetServiceStart();
+  EXPECT_FALSE(CreateSensor(SensorType::ACCELEROMETER));
+}
+
+// Tests sensor is returned if supported.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorIsSupported) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+  EXPECT_EQ(SensorType::AMBIENT_LIGHT, sensor->GetType());
+}
+
+// Tests that PlatformSensor::StartListening fails when provided reporting
+// frequency is above hardware capabilities.
+TEST_F(PlatformSensorAndProviderLinuxTest, StartFails) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(10);
+  EXPECT_FALSE(sensor->StartListening(client.get(), configuration));
+}
+
+// Tests that PlatformSensor::StartListening succeeds and notification about
+// modified sensor reading is sent to the PlatformSensor::Client interface.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorStarted) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(5);
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  WaitOnSensorReadingChangedEvent(client.get());
+  EXPECT_TRUE(sensor->StopListening(client.get(), configuration));
+}
+
+// Tests that OnSensorError is called when sensor is disconnected.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorRemoved) {
+  double sensor_value[3] = {1};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(5);
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  GenerateDeviceRemovedEvent(sensors_dir_.GetPath());
+  WaitOnSensorErrorEvent(client.get());
+}
+
+// Tests that sensor is not returned if not connected and
+// is created after it has been added.
+TEST_F(PlatformSensorAndProviderLinuxTest, SensorAddedAndRemoved) {
+  double sensor_value[3] = {1, 2, 4};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto als_sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(als_sensor);
+  auto gyro_sensor = CreateSensor(SensorType::GYROSCOPE);
+  EXPECT_FALSE(gyro_sensor);
+
+  InitializeSupportedSensor(SensorType::GYROSCOPE, kGyroscopeFrequencyValue,
+                            kGyroscopeOffsetValue, kGyroscopeScalingValue,
+                            sensor_value);
+  udev_device* dev = nullptr;
+  manager_->DeviceAdded(dev /* not used */);
+  base::RunLoop().RunUntilIdle();
+  gyro_sensor = CreateSensor(SensorType::GYROSCOPE);
+  EXPECT_TRUE(gyro_sensor);
+  EXPECT_EQ(gyro_sensor->GetType(), SensorType::GYROSCOPE);
+}
+
+// Checks the main fields of all sensors and initialized right.
+TEST_F(PlatformSensorAndProviderLinuxTest, CheckAllSupportedSensors) {
+  double sensor_value[3] = {1, 2, 3};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeSupportedSensor(
+      SensorType::ACCELEROMETER, kAccelerometerFrequencyValue,
+      kAccelerometerOffsetValue, kAccelerometerScalingValue, sensor_value);
+  InitializeSupportedSensor(SensorType::GYROSCOPE, kGyroscopeFrequencyValue,
+                            kGyroscopeOffsetValue, kGyroscopeScalingValue,
+                            sensor_value);
+  InitializeSupportedSensor(
+      SensorType::MAGNETOMETER, kMagnetometerFrequencyValue,
+      kMagnetometerOffsetValue, kMagnetometerScalingValue, sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto als_sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(als_sensor);
+  EXPECT_EQ(als_sensor->GetType(), SensorType::AMBIENT_LIGHT);
+  EXPECT_THAT(als_sensor->GetDefaultConfiguration().frequency(),
+              kDefaultAmbientLightFrequencyHz);
+
+  auto accel_sensor = CreateSensor(SensorType::ACCELEROMETER);
+  EXPECT_TRUE(accel_sensor);
+  EXPECT_EQ(accel_sensor->GetType(), SensorType::ACCELEROMETER);
+  EXPECT_THAT(accel_sensor->GetDefaultConfiguration().frequency(),
+              kAccelerometerFrequencyValue);
+
+  auto gyro_sensor = CreateSensor(SensorType::GYROSCOPE);
+  EXPECT_TRUE(gyro_sensor);
+  EXPECT_EQ(gyro_sensor->GetType(), SensorType::GYROSCOPE);
+  EXPECT_THAT(gyro_sensor->GetDefaultConfiguration().frequency(),
+              kGyroscopeFrequencyValue);
+
+  auto magn_sensor = CreateSensor(SensorType::MAGNETOMETER);
+  EXPECT_TRUE(magn_sensor);
+  EXPECT_EQ(magn_sensor->GetType(), SensorType::MAGNETOMETER);
+  EXPECT_THAT(magn_sensor->GetDefaultConfiguration().frequency(),
+              kMagnetometerFrequencyValue);
+}
+
+// Tests that GetMaximumSupportedFrequency provides correct value.
+TEST_F(PlatformSensorAndProviderLinuxTest, GetMaximumSupportedFrequency) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(
+      SensorType::ACCELEROMETER, kAccelerometerFrequencyValue,
+      kAccelerometerOffsetValue, kAccelerometerScalingValue, sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::ACCELEROMETER);
+  EXPECT_TRUE(sensor);
+  EXPECT_THAT(sensor->GetMaximumSupportedFrequency(),
+              kAccelerometerFrequencyValue);
+}
+
+// Tests that GetMaximumSupportedFrequency provides correct value when
+// OS does not provide any information about frequency.
+TEST_F(PlatformSensorAndProviderLinuxTest,
+       GetMaximumSupportedFrequencyDefault) {
+  double sensor_value[3] = {5};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+  EXPECT_EQ(SensorType::AMBIENT_LIGHT, sensor->GetType());
+  EXPECT_THAT(sensor->GetMaximumSupportedFrequency(),
+              kDefaultAmbientLightFrequencyHz);
+}
+
+// Tests that Ambient Light sensor is correctly read.
+TEST_F(PlatformSensorAndProviderLinuxTest, CheckAmbientLightReadings) {
+  mojo::ScopedSharedBufferHandle handle = provider_->CloneSharedBufferHandle();
+  mojo::ScopedSharedBufferMapping mapping = handle->MapAtOffset(
+      sizeof(SensorReadingSharedBuffer),
+      SensorReadingSharedBuffer::GetOffset(SensorType::AMBIENT_LIGHT));
+
+  double sensor_value[3] = {22};
+  InitializeSupportedSensor(SensorType::AMBIENT_LIGHT, kZero, kZero, kZero,
+                            sensor_value);
+
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::AMBIENT_LIGHT);
+  EXPECT_TRUE(sensor);
+  EXPECT_EQ(sensor->GetReportingMode(), mojom::ReportingMode::ON_CHANGE);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(
+      sensor->GetMaximumSupportedFrequency());
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  WaitOnSensorReadingChangedEvent(client.get());
+  EXPECT_TRUE(sensor->StopListening(client.get(), configuration));
+
+  SensorReadingSharedBuffer* buffer =
+      static_cast<SensorReadingSharedBuffer*>(mapping.get());
+  EXPECT_THAT(buffer->reading.values[0], sensor_value[0]);
+}
+
+// Tests that Accelerometer readings are correctly converted.
+TEST_F(PlatformSensorAndProviderLinuxTest,
+       CheckAccelerometerReadingConversion) {
+  mojo::ScopedSharedBufferHandle handle = provider_->CloneSharedBufferHandle();
+  mojo::ScopedSharedBufferMapping mapping = handle->MapAtOffset(
+      sizeof(SensorReadingSharedBuffer),
+      SensorReadingSharedBuffer::GetOffset(SensorType::ACCELEROMETER));
+
+  double sensor_values[3] = {4.5, -2.45, -3.29};
+  InitializeSupportedSensor(
+      SensorType::ACCELEROMETER, kAccelerometerFrequencyValue,
+      kAccelerometerOffsetValue, kAccelerometerScalingValue, sensor_values);
+
+  // As long as WaitOnSensorReadingChangedEvent() waits until client gets a
+  // a notification about readings changed, the frequency file must be deleted
+  // to make the sensor device manager identify this sensor with ON_CHANGE
+  // reporting mode. This will allow the MockPlatformSensorClient to
+  // receive a notification and test if reading values are right. Otherwise
+  // the test will not know when data is ready.
+  SensorPathsLinux data;
+  EXPECT_TRUE(InitSensorData(SensorType::ACCELEROMETER, &data));
+  base::FilePath frequency_file = base::FilePath(sensors_dir_.GetPath())
+                                      .Append(data.sensor_frequency_file_name);
+  DeleteFile(frequency_file);
+
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::ACCELEROMETER);
+  EXPECT_TRUE(sensor);
+  // The reporting mode is ON_CHANGE only for this test.
+  EXPECT_EQ(sensor->GetReportingMode(), mojom::ReportingMode::ON_CHANGE);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(10);
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  WaitOnSensorReadingChangedEvent(client.get());
+  EXPECT_TRUE(sensor->StopListening(client.get(), configuration));
+
+  SensorReadingSharedBuffer* buffer =
+      static_cast<SensorReadingSharedBuffer*>(mapping.get());
+#if defined(OS_CHROMEOS)
+  double scaling = kMeanGravity / kAccelerometerScalingValue;
+  EXPECT_THAT(buffer->reading.values[0], scaling * sensor_values[0]);
+  EXPECT_THAT(buffer->reading.values[1], scaling * sensor_values[1]);
+  EXPECT_THAT(buffer->reading.values[2], scaling * sensor_values[2]);
+#else
+  double scaling = kAccelerometerScalingValue + kAccelerometerOffsetValue;
+  EXPECT_THAT(buffer->reading.values[0], -scaling * sensor_values[0]);
+  EXPECT_THAT(buffer->reading.values[1], -scaling * sensor_values[1]);
+  EXPECT_THAT(buffer->reading.values[2], -scaling * sensor_values[2]);
+#endif
+}
+
+// Tests that Gyroscope readings are correctly converted.
+TEST_F(PlatformSensorAndProviderLinuxTest, CheckGyroscopeReadingConversion) {
+  mojo::ScopedSharedBufferHandle handle = provider_->CloneSharedBufferHandle();
+  mojo::ScopedSharedBufferMapping mapping = handle->MapAtOffset(
+      sizeof(SensorReadingSharedBuffer),
+      SensorReadingSharedBuffer::GetOffset(SensorType::GYROSCOPE));
+
+  double sensor_values[3] = {2.2, -3.8, -108.7};
+  InitializeSupportedSensor(SensorType::GYROSCOPE, kGyroscopeFrequencyValue,
+                            kGyroscopeOffsetValue, kGyroscopeScalingValue,
+                            sensor_values);
+
+  // As long as WaitOnSensorReadingChangedEvent() waits until client gets a
+  // a notification about readings changed, the frequency file must be deleted
+  // to make the sensor device manager identify this sensor with ON_CHANGE
+  // reporting mode. This will allow the MockPlatformSensorClient to
+  // receive a notification and test if reading values are right. Otherwise
+  // the test will not know when data is ready.
+  SensorPathsLinux data;
+  EXPECT_TRUE(InitSensorData(SensorType::GYROSCOPE, &data));
+  base::FilePath frequency_file = base::FilePath(sensors_dir_.GetPath())
+                                      .Append(data.sensor_frequency_file_name);
+  DeleteFile(frequency_file);
+
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::GYROSCOPE);
+  EXPECT_TRUE(sensor);
+  // The reporting mode is ON_CHANGE only for this test.
+  EXPECT_EQ(sensor->GetReportingMode(), mojom::ReportingMode::ON_CHANGE);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(10);
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  WaitOnSensorReadingChangedEvent(client.get());
+  EXPECT_TRUE(sensor->StopListening(client.get(), configuration));
+
+  SensorReadingSharedBuffer* buffer =
+      static_cast<SensorReadingSharedBuffer*>(mapping.get());
+#if defined(OS_CHROMEOS)
+  double scaling =
+      kMeanGravity * kRadiansInDegreesPerSecond / kGyroscopeScalingValue;
+  EXPECT_THAT(buffer->reading.values[0], -scaling * sensor_values[0]);
+  EXPECT_THAT(buffer->reading.values[1], -scaling * sensor_values[1]);
+  EXPECT_THAT(buffer->reading.values[2], -scaling * sensor_values[2]);
+#else
+  double scaling = kGyroscopeScalingValue + kGyroscopeOffsetValue;
+  EXPECT_THAT(buffer->reading.values[0], scaling * sensor_values[0]);
+  EXPECT_THAT(buffer->reading.values[1], scaling * sensor_values[1]);
+  EXPECT_THAT(buffer->reading.values[2], scaling * sensor_values[2]);
+#endif
+}
+
+// Tests that Magnetometer readings are correctly converted.
+TEST_F(PlatformSensorAndProviderLinuxTest, CheckMagnetometerReadingConversion) {
+  mojo::ScopedSharedBufferHandle handle = provider_->CloneSharedBufferHandle();
+  mojo::ScopedSharedBufferMapping mapping = handle->MapAtOffset(
+      sizeof(SensorReadingSharedBuffer),
+      SensorReadingSharedBuffer::GetOffset(SensorType::MAGNETOMETER));
+
+  double sensor_values[3] = {2.2, -3.8, -108.7};
+  InitializeSupportedSensor(
+      SensorType::MAGNETOMETER, kMagnetometerFrequencyValue,
+      kMagnetometerOffsetValue, kMagnetometerScalingValue, sensor_values);
+
+  // As long as WaitOnSensorReadingChangedEvent() waits until client gets a
+  // a notification about readings changed, the frequency file must be deleted
+  // to make the sensor device manager identify this sensor with ON_CHANGE
+  // reporting mode. This will allow the MockPlatformSensorClient to
+  // receive a notification and test if reading values are right. Otherwise
+  // the test will not know when data is ready.
+  SensorPathsLinux data;
+  EXPECT_TRUE(InitSensorData(SensorType::MAGNETOMETER, &data));
+  base::FilePath frequency_file = base::FilePath(sensors_dir_.GetPath())
+                                      .Append(data.sensor_frequency_file_name);
+  DeleteFile(frequency_file);
+
+  InitializeMockUdevMethods(sensors_dir_.GetPath());
+  SetServiceStart();
+
+  auto sensor = CreateSensor(SensorType::MAGNETOMETER);
+  EXPECT_TRUE(sensor);
+  // The reporting mode is ON_CHANGE only for this test.
+  EXPECT_EQ(sensor->GetReportingMode(), mojom::ReportingMode::ON_CHANGE);
+
+  auto client = base::MakeUnique<NiceMock<MockPlatformSensorClient>>(sensor);
+  PlatformSensorConfiguration configuration(10);
+  EXPECT_TRUE(sensor->StartListening(client.get(), configuration));
+  WaitOnSensorReadingChangedEvent(client.get());
+  EXPECT_TRUE(sensor->StopListening(client.get(), configuration));
+
+  SensorReadingSharedBuffer* buffer =
+      static_cast<SensorReadingSharedBuffer*>(mapping.get());
+  double scaling = (kMagnetometerScalingValue + kMagnetometerOffsetValue) *
+                   kMicroteslaInGauss;
+  EXPECT_THAT(buffer->reading.values[0], scaling * sensor_values[0]);
+  EXPECT_THAT(buffer->reading.values[1], scaling * sensor_values[1]);
+  EXPECT_THAT(buffer->reading.values[2], scaling * sensor_values[2]);
+}
+
+}  // namespace device