Implemented sensor class

Sensor class was introduced, it monitors
xyz.openbmc_project.Sensor.Value, for change and notifies all
listeners.

Tested:
  - Unit tested with service stub that provides dbus interface
    xyz.openbmc_project.Sensor.Value
  - All changes are delivered to listeners
  - All other unit tests are passing

Change-Id: I8c9d58cc986c1fe2a4d2386815d559814016efa6
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/meson.build b/meson.build
index 8d0b018..d3472da 100644
--- a/meson.build
+++ b/meson.build
@@ -29,7 +29,12 @@
     language: 'cpp'
 )
 
-boost = dependency('boost', version: '>=1.74.0', required: false)
+boost = dependency(
+  'boost',
+  version: '>=1.74.0',
+  required: false,
+  modules: ['coroutine'])
+
 if not boost.found()
     subproject('boost', required: false)
     boost  = declare_dependency(include_directories: 'subprojects/boost_1_74_0')
@@ -70,6 +75,7 @@
         'src/persistent_json_storage.cpp',
         'src/report.cpp',
         'src/report_manager.cpp',
+        'src/sensor.cpp',
         'src/sensor_cache.cpp',
     ],
     dependencies: [
diff --git a/src/interfaces/sensor.hpp b/src/interfaces/sensor.hpp
index dbeb158..07c7897 100644
--- a/src/interfaces/sensor.hpp
+++ b/src/interfaces/sensor.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <chrono>
+#include <memory>
 #include <ostream>
 #include <string>
 #include <string_view>
@@ -8,6 +10,8 @@
 namespace interfaces
 {
 
+class SensorListener;
+
 class Sensor
 {
   public:
@@ -28,11 +32,17 @@
             return std::tie(type, service, path) <
                    std::tie(other.type, other.service, other.path);
         }
+
+        inline std::string str() const
+        {
+            return type + ":" + service + ":" + path;
+        }
     };
 
     virtual ~Sensor() = default;
 
     virtual Id id() const = 0;
+    virtual void registerForUpdates(const std::weak_ptr<SensorListener>&) = 0;
 };
 
 } // namespace interfaces
diff --git a/src/interfaces/sensor_listener.hpp b/src/interfaces/sensor_listener.hpp
new file mode 100644
index 0000000..9a2f0a2
--- /dev/null
+++ b/src/interfaces/sensor_listener.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <optional>
+
+namespace interfaces
+{
+
+class Sensor;
+
+class SensorListener
+{
+  public:
+    virtual ~SensorListener() = default;
+
+    virtual void sensorUpdated(interfaces::Sensor&, uint64_t) = 0;
+    virtual void sensorUpdated(interfaces::Sensor&, uint64_t, double) = 0;
+};
+
+} // namespace interfaces
diff --git a/src/sensor.cpp b/src/sensor.cpp
new file mode 100644
index 0000000..d38fbd9
--- /dev/null
+++ b/src/sensor.cpp
@@ -0,0 +1,168 @@
+#include "sensor.hpp"
+
+#include "utils/detached_timer.hpp"
+
+#include <boost/container/flat_map.hpp>
+#include <phosphor-logging/log.hpp>
+#include <sdbusplus/asio/property.hpp>
+#include <sdbusplus/bus/match.hpp>
+
+#include <functional>
+#include <iostream>
+
+Sensor::Sensor(interfaces::Sensor::Id sensorId, boost::asio::io_context& ioc,
+               const std::shared_ptr<sdbusplus::asio::connection>& bus) :
+    sensorId(std::move(sensorId)),
+    ioc(ioc), bus(bus)
+{}
+
+Sensor::Id Sensor::makeId(std::string_view service, std::string_view path)
+{
+    return Id("Sensor", service, path);
+}
+
+Sensor::Id Sensor::id() const
+{
+    return sensorId;
+}
+
+void Sensor::async_read()
+{
+    uniqueCall([this](auto lock) { async_read(std::move(lock)); });
+}
+
+void Sensor::async_read(std::shared_ptr<utils::UniqueCall::Lock> lock)
+{
+    makeSignalMonitor();
+
+    sdbusplus::asio::getProperty<double>(
+        *bus, sensorId.service, sensorId.path,
+        "xyz.openbmc_project.Sensor.Value", "Value",
+        [lock, id = sensorId,
+         weakSelf = weak_from_this()](boost::system::error_code ec) {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "DBus 'GetProperty' call failed on Sensor Value",
+                phosphor::logging::entry("sensor=%s, ec=%lu", id.str().c_str(),
+                                         ec.value()));
+
+            if (auto self = weakSelf.lock())
+            {
+
+                constexpr auto retryIntervalAfterFailedRead =
+                    std::chrono::seconds(30);
+                utils::makeDetachedTimer(
+                    self->ioc, retryIntervalAfterFailedRead, [weakSelf] {
+                        if (auto self = weakSelf.lock())
+                        {
+                            self->async_read();
+                        }
+                    });
+            }
+        },
+        [lock, weakSelf = weak_from_this()](double newValue) {
+            if (auto self = weakSelf.lock())
+            {
+                self->updateValue(newValue);
+            }
+        });
+}
+
+void Sensor::registerForUpdates(
+    const std::weak_ptr<interfaces::SensorListener>& weakListener)
+{
+    if (auto listener = weakListener.lock())
+    {
+        listeners.emplace_back(weakListener);
+
+        if (value)
+        {
+            listener->sensorUpdated(*this, timestamp, *value);
+        }
+        else
+        {
+            async_read();
+        }
+    }
+}
+
+void Sensor::updateValue(double newValue)
+{
+    timestamp = std::time(0);
+
+    if (value == newValue)
+    {
+        for (const auto& weakListener : listeners)
+        {
+            if (auto listener = weakListener.lock())
+            {
+                listener->sensorUpdated(*this, timestamp);
+            }
+        }
+    }
+    else
+    {
+        value = newValue;
+
+        for (const auto& weakListener : listeners)
+        {
+            if (auto listener = weakListener.lock())
+            {
+                listener->sensorUpdated(*this, timestamp, *value);
+            }
+        }
+    }
+}
+
+void Sensor::makeSignalMonitor()
+{
+    if (signalMonitor)
+    {
+        return;
+    }
+
+    using namespace std::string_literals;
+
+    const auto param = "type='signal',member='PropertiesChanged',path='"s +
+                       sensorId.path +
+                       "',arg0='xyz.openbmc_project.Sensor.Value'"s;
+
+    signalMonitor = std::make_unique<sdbusplus::bus::match::match>(
+        *bus, param,
+        [weakSelf = weak_from_this()](sdbusplus::message::message& message) {
+            signalProc(weakSelf, message);
+        });
+}
+
+void Sensor::signalProc(const std::weak_ptr<Sensor>& weakSelf,
+                        sdbusplus::message::message& message)
+{
+    if (auto self = weakSelf.lock())
+    {
+        std::string iface;
+        boost::container::flat_map<std::string, ValueVariant>
+            changed_properties;
+        std::vector<std::string> invalidated_properties;
+
+        message.read(iface, changed_properties, invalidated_properties);
+
+        if (iface == "xyz.openbmc_project.Sensor.Value")
+        {
+            const auto it = changed_properties.find("Value");
+            if (it != changed_properties.end())
+            {
+                if (auto val = std::get_if<double>(&it->second))
+                {
+                    self->updateValue(*val);
+                }
+                else
+                {
+                    phosphor::logging::log<phosphor::logging::level::ERR>(
+                        "Failed to receive Value from Sensor "
+                        "PropertiesChanged signal",
+                        phosphor::logging::entry("sensor=%s",
+                                                 self->sensorId.path.c_str()));
+                }
+            }
+        }
+    }
+}
diff --git a/src/sensor.hpp b/src/sensor.hpp
new file mode 100644
index 0000000..1374c54
--- /dev/null
+++ b/src/sensor.hpp
@@ -0,0 +1,52 @@
+#pragma once
+
+#include "interfaces/sensor.hpp"
+#include "interfaces/sensor_listener.hpp"
+#include "utils/unique_call.hpp"
+
+#include <boost/asio/high_resolution_timer.hpp>
+#include <sdbusplus/asio/connection.hpp>
+
+#include <memory>
+
+class Sensor final :
+    public interfaces::Sensor,
+    public std::enable_shared_from_this<Sensor>
+{
+    using ValueVariant = std::variant<std::monostate, double>;
+
+  public:
+    Sensor(interfaces::Sensor::Id sensorId, boost::asio::io_context& ioc,
+           const std::shared_ptr<sdbusplus::asio::connection>& bus);
+
+    Sensor(const Sensor&) = delete;
+    Sensor& operator=(const Sensor&) = delete;
+
+    static Id makeId(std::string_view service, std::string_view path);
+
+    Id id() const override;
+    void registerForUpdates(
+        const std::weak_ptr<interfaces::SensorListener>& weakListener) override;
+
+  private:
+    static std::optional<double> readValue(const ValueVariant& v);
+    static void signalProc(const std::weak_ptr<Sensor>& weakSelf,
+                           sdbusplus::message::message&);
+
+    void async_read();
+    void async_read(std::shared_ptr<utils::UniqueCall::Lock>);
+    void makeSignalMonitor();
+    void updateValue(double);
+
+    interfaces::Sensor::Id sensorId;
+    boost::asio::io_context& ioc;
+    std::shared_ptr<sdbusplus::asio::connection> bus;
+    std::chrono::milliseconds timerInterval = std::chrono::milliseconds(0);
+    std::optional<boost::asio::high_resolution_timer> timer;
+
+    utils::UniqueCall uniqueCall;
+    std::vector<std::weak_ptr<interfaces::SensorListener>> listeners;
+    uint64_t timestamp = 0;
+    std::optional<double> value;
+    std::unique_ptr<sdbusplus::bus::match::match> signalMonitor;
+};
diff --git a/src/utils/detached_timer.hpp b/src/utils/detached_timer.hpp
new file mode 100644
index 0000000..21343f9
--- /dev/null
+++ b/src/utils/detached_timer.hpp
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/spawn.hpp>
+#include <boost/asio/steady_timer.hpp>
+
+#include <chrono>
+
+namespace utils
+{
+
+template <class F>
+void makeDetachedTimer(boost::asio::io_context& ioc,
+                       std::chrono::milliseconds delay, F&& fun)
+{
+    auto timer = std::make_unique<boost::asio::steady_timer>(ioc);
+    timer->expires_after(delay);
+    timer->async_wait([timer = std::move(timer),
+                       fun = std::move(fun)](boost::system::error_code ec) {
+        if (ec)
+        {
+            return;
+        }
+        fun();
+    });
+}
+
+} // namespace utils
diff --git a/src/utils/unique_call.hpp b/src/utils/unique_call.hpp
new file mode 100644
index 0000000..db10786
--- /dev/null
+++ b/src/utils/unique_call.hpp
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <memory>
+#include <utility>
+
+namespace utils
+{
+
+class UniqueCall
+{
+  public:
+    struct Lock
+    {};
+
+    template <class Functor, class... Args>
+    void operator()(Functor&& functor, Args&&... args)
+    {
+        if (lock.expired())
+        {
+            auto l = std::make_shared<Lock>();
+            lock = l;
+            functor(std::move(l), std::forward<Args>(args)...);
+        }
+    }
+
+  private:
+    std::weak_ptr<Lock> lock;
+};
+
+} // namespace utils
diff --git a/tests/meson.build b/tests/meson.build
index 08a6e6c..89e5088 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -6,8 +6,7 @@
         gtest_dep = declare_dependency(
             dependencies: [
                 dependency('threads'),
-                gtest_proj.dependency('gtest'),
-                gtest_proj.dependency('gtest_main'),
+                gtest_proj.dependency('gtest')
             ]
         )
         gmock_dep = gtest_proj.dependency('gmock')
@@ -27,9 +26,16 @@
             '../src/persistent_json_storage.cpp',
             '../src/report.cpp',
             '../src/report_manager.cpp',
+            '../src/sensor.cpp',
             '../src/sensor_cache.cpp',
+            'src/dbus_environment.cpp',
+            'src/main.cpp',
+            'src/stubs/dbus_sensor_object.cpp',
+            'src/test_detached_timer.cpp',
             'src/test_persistent_json_storage.cpp',
+            'src/test_sensor.cpp',
             'src/test_sensor_cache.cpp',
+            'src/test_unique_call.cpp',
             'src/utils/generate_unique_mock_id.cpp',
         ],
         dependencies: [
diff --git a/tests/src/dbus_environment.cpp b/tests/src/dbus_environment.cpp
new file mode 100644
index 0000000..ab749db
--- /dev/null
+++ b/tests/src/dbus_environment.cpp
@@ -0,0 +1,121 @@
+#include "dbus_environment.hpp"
+
+#include <future>
+#include <thread>
+
+DbusEnvironment::~DbusEnvironment()
+{
+    teardown();
+}
+
+void DbusEnvironment::SetUp()
+{
+    if (setUp == false)
+    {
+        setUp = true;
+
+        bus = std::make_shared<sdbusplus::asio::connection>(ioc);
+        bus->request_name(serviceName());
+
+        objServer = std::make_unique<sdbusplus::asio::object_server>(bus);
+    }
+}
+
+void DbusEnvironment::TearDown()
+{
+    ioc.poll();
+
+    futures.clear();
+}
+
+void DbusEnvironment::teardown()
+{
+    if (setUp == true)
+    {
+        setUp = false;
+
+        objServer = nullptr;
+        bus = nullptr;
+    }
+}
+
+boost::asio::io_context& DbusEnvironment::getIoc()
+{
+    return ioc;
+}
+
+std::shared_ptr<sdbusplus::asio::connection> DbusEnvironment::getBus()
+{
+    return bus;
+}
+
+std::shared_ptr<sdbusplus::asio::object_server> DbusEnvironment::getObjServer()
+{
+    return objServer;
+}
+
+const char* DbusEnvironment::serviceName()
+{
+    return "telemetry.ut";
+}
+
+std::function<void()> DbusEnvironment::setPromise(std::string_view name)
+{
+    auto promise = std::make_shared<std::promise<bool>>();
+
+    {
+        futures[std::string(name)].emplace_back(promise->get_future());
+    }
+
+    return [p = std::move(promise)]() { p->set_value(true); };
+}
+
+bool DbusEnvironment::waitForFuture(std::string_view name,
+                                    std::chrono::milliseconds timeout)
+{
+    return waitForFuture(getFuture(name), timeout).value_or(false);
+}
+
+std::future<bool> DbusEnvironment::getFuture(std::string_view name)
+{
+    auto& data = futures[std::string(name)];
+    auto it = data.begin();
+
+    if (it != data.end())
+    {
+        auto result = std::move(*it);
+        data.erase(it);
+        return result;
+    }
+
+    return {};
+}
+
+void DbusEnvironment::sleepFor(std::chrono::milliseconds timeout)
+{
+    auto end = std::chrono::high_resolution_clock::now() + timeout;
+
+    while (std::chrono::high_resolution_clock::now() < end)
+    {
+        synchronizeIoc();
+        std::this_thread::yield();
+    }
+
+    synchronizeIoc();
+}
+
+std::chrono::milliseconds
+    DbusEnvironment::measureTime(std::function<void()> fun)
+{
+    auto begin = std::chrono::high_resolution_clock::now();
+    fun();
+    auto end = std::chrono::high_resolution_clock::now();
+
+    return std::chrono::duration_cast<std::chrono::milliseconds>(end - begin);
+}
+
+boost::asio::io_context DbusEnvironment::ioc;
+std::shared_ptr<sdbusplus::asio::connection> DbusEnvironment::bus;
+std::shared_ptr<sdbusplus::asio::object_server> DbusEnvironment::objServer;
+std::map<std::string, std::vector<std::future<bool>>> DbusEnvironment::futures;
+bool DbusEnvironment::setUp = false;
diff --git a/tests/src/dbus_environment.hpp b/tests/src/dbus_environment.hpp
new file mode 100644
index 0000000..d039922
--- /dev/null
+++ b/tests/src/dbus_environment.hpp
@@ -0,0 +1,84 @@
+#include <sdbusplus/asio/object_server.hpp>
+
+#include <future>
+#include <thread>
+
+#include <gmock/gmock.h>
+
+class DbusEnvironment : public ::testing::Environment
+{
+  public:
+    ~DbusEnvironment();
+
+    void SetUp() override;
+    void TearDown() override;
+    void teardown();
+
+    static boost::asio::io_context& getIoc();
+    static std::shared_ptr<sdbusplus::asio::connection> getBus();
+    static std::shared_ptr<sdbusplus::asio::object_server> getObjServer();
+    static const char* serviceName();
+    static std::function<void()> setPromise(std::string_view name);
+    static void sleepFor(std::chrono::milliseconds);
+    static std::chrono::milliseconds measureTime(std::function<void()>);
+
+    static void synchronizeIoc()
+    {
+        while (ioc.poll() > 0)
+        {
+        }
+    }
+
+    template <class Functor>
+    static void synchronizedPost(Functor&& functor)
+    {
+        boost::asio::post(ioc, std::forward<Functor>(functor));
+        synchronizeIoc();
+    }
+
+    template <class T>
+    static std::optional<T> waitForFuture(
+        std::future<T> future,
+        std::chrono::milliseconds timeout = std::chrono::seconds(10))
+    {
+        constexpr auto precission = std::chrono::milliseconds(10);
+        auto elapsed = std::chrono::milliseconds(0);
+
+        while (future.valid() && elapsed < timeout)
+        {
+            synchronizeIoc();
+
+            try
+            {
+                if (future.wait_for(precission) == std::future_status::ready)
+                {
+                    return future.get();
+                }
+                else
+                {
+                    elapsed += precission;
+                }
+            }
+            catch (const std::future_error& e)
+            {
+                std::cerr << e.what() << "\n";
+                return {};
+            }
+        }
+
+        return {};
+    }
+
+    static bool waitForFuture(
+        std::string_view name,
+        std::chrono::milliseconds timeout = std::chrono::seconds(10));
+
+  private:
+    static std::future<bool> getFuture(std::string_view name);
+
+    static boost::asio::io_context ioc;
+    static std::shared_ptr<sdbusplus::asio::connection> bus;
+    static std::shared_ptr<sdbusplus::asio::object_server> objServer;
+    static std::map<std::string, std::vector<std::future<bool>>> futures;
+    static bool setUp;
+};
diff --git a/tests/src/main.cpp b/tests/src/main.cpp
new file mode 100644
index 0000000..6e29319
--- /dev/null
+++ b/tests/src/main.cpp
@@ -0,0 +1,16 @@
+#include "dbus_environment.hpp"
+
+#include <gmock/gmock.h>
+
+int main(int argc, char** argv)
+{
+    auto env = new DbusEnvironment;
+
+    testing::InitGoogleTest(&argc, argv);
+    testing::AddGlobalTestEnvironment(env);
+    auto ret = RUN_ALL_TESTS();
+
+    env->teardown();
+
+    return ret;
+}
diff --git a/tests/src/mocks/json_storage_mock.hpp b/tests/src/mocks/json_storage_mock.hpp
index 295bc94..99ecd41 100644
--- a/tests/src/mocks/json_storage_mock.hpp
+++ b/tests/src/mocks/json_storage_mock.hpp
@@ -7,8 +7,11 @@
 class StorageMock : public interfaces::JsonStorage
 {
   public:
-    MOCK_METHOD2(store, void(const FilePath&, const nlohmann::json&));
-    MOCK_METHOD1(remove, bool(const FilePath&));
-    MOCK_CONST_METHOD1(load, std::optional<nlohmann::json>(const FilePath&));
-    MOCK_CONST_METHOD1(list, std::vector<FilePath>(const DirectoryPath&));
+    MOCK_METHOD(void, store, (const FilePath&, const nlohmann::json&),
+                (override));
+    MOCK_METHOD(bool, remove, (const FilePath&), (override));
+    MOCK_METHOD(std::optional<nlohmann::json>, load, (const FilePath&),
+                (const, override));
+    MOCK_METHOD(std::vector<FilePath>, list, (const DirectoryPath&),
+                (const, override));
 };
diff --git a/tests/src/mocks/sensor_listener_mock.hpp b/tests/src/mocks/sensor_listener_mock.hpp
new file mode 100644
index 0000000..b8f1ef5
--- /dev/null
+++ b/tests/src/mocks/sensor_listener_mock.hpp
@@ -0,0 +1,29 @@
+#pragma once
+
+#include "interfaces/sensor_listener.hpp"
+
+#include <gmock/gmock.h>
+
+class SensorListenerMock : public interfaces::SensorListener
+{
+  public:
+    void delegateIgnoringArgs()
+    {
+        using namespace testing;
+
+        ON_CALL(*this, sensorUpdated(_, _)).WillByDefault(Invoke([this] {
+            sensorUpdated();
+        }));
+
+        ON_CALL(*this, sensorUpdated(_, _, _)).WillByDefault(Invoke([this] {
+            sensorUpdated();
+        }));
+    }
+
+    MOCK_METHOD(void, sensorUpdated, (interfaces::Sensor&, uint64_t),
+                (override));
+    MOCK_METHOD(void, sensorUpdated, (interfaces::Sensor&, uint64_t, double),
+                (override));
+
+    MOCK_METHOD(void, sensorUpdated, (), ());
+};
diff --git a/tests/src/mocks/sensor_mock.hpp b/tests/src/mocks/sensor_mock.hpp
index 9e8d7f3..0dcb2b5 100644
--- a/tests/src/mocks/sensor_mock.hpp
+++ b/tests/src/mocks/sensor_mock.hpp
@@ -20,7 +20,9 @@
         return Id("SensorMock", service, path);
     }
 
-    MOCK_CONST_METHOD0(id, Id());
+    MOCK_METHOD(Id, id, (), (const, override));
+    MOCK_METHOD(void, registerForUpdates,
+                (const std::weak_ptr<interfaces::SensorListener>&), (override));
 
     const uint64_t mockId = generateUniqueMockId();
 
diff --git a/tests/src/stubs/dbus_sensor_object.cpp b/tests/src/stubs/dbus_sensor_object.cpp
new file mode 100644
index 0000000..c3d4170
--- /dev/null
+++ b/tests/src/stubs/dbus_sensor_object.cpp
@@ -0,0 +1,59 @@
+#include "dbus_sensor_object.hpp"
+
+#include <boost/asio.hpp>
+#include <sdbusplus/asio/connection.hpp>
+#include <sdbusplus/asio/object_server.hpp>
+#include <sdbusplus/bus.hpp>
+
+namespace stubs
+{
+
+DbusSensorObject::DbusSensorObject(
+    boost::asio::io_context& ioc,
+    const std::shared_ptr<sdbusplus::asio::connection>& bus,
+    const std::shared_ptr<sdbusplus::asio::object_server>& objServer) :
+    ioc(ioc),
+    bus(bus), objServer(objServer)
+{
+    sensorIface = objServer->add_interface(path(), interface());
+
+    sensorIface->register_property_r(property.value(), double{},
+                                     sdbusplus::vtable::property_::emits_change,
+                                     [this](const auto&) { return value; });
+
+    sensorIface->initialize();
+}
+
+DbusSensorObject::~DbusSensorObject()
+{
+    objServer->remove_interface(sensorIface);
+}
+
+void DbusSensorObject::setValue(double v)
+{
+    value = v;
+
+    sensorIface->signal_property(property.value());
+}
+
+double DbusSensorObject::getValue() const
+{
+    return value;
+}
+
+const char* DbusSensorObject::path()
+{
+    return "/telemetry/ut/DbusSensorObject";
+}
+
+const char* DbusSensorObject::interface()
+{
+    return "xyz.openbmc_project.Sensor.Value";
+}
+
+const char* DbusSensorObject::Properties::value()
+{
+    return "Value";
+}
+
+} // namespace stubs
diff --git a/tests/src/stubs/dbus_sensor_object.hpp b/tests/src/stubs/dbus_sensor_object.hpp
new file mode 100644
index 0000000..99271fa
--- /dev/null
+++ b/tests/src/stubs/dbus_sensor_object.hpp
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <boost/asio.hpp>
+#include <sdbusplus/asio/connection.hpp>
+#include <sdbusplus/asio/object_server.hpp>
+#include <sdbusplus/bus.hpp>
+
+namespace stubs
+{
+
+class DbusSensorObject
+{
+  public:
+    DbusSensorObject(
+        boost::asio::io_context& ioc,
+        const std::shared_ptr<sdbusplus::asio::connection>& bus,
+        const std::shared_ptr<sdbusplus::asio::object_server>& objServer);
+    ~DbusSensorObject();
+
+    static const char* path();
+    static const char* interface();
+
+    void setValue(double);
+    double getValue() const;
+
+    struct Properties
+    {
+        static const char* value();
+    };
+
+    static constexpr Properties property = {};
+
+  private:
+    boost::asio::io_context& ioc;
+    std::shared_ptr<sdbusplus::asio::connection> bus;
+    std::shared_ptr<sdbusplus::asio::object_server> objServer;
+
+    std::shared_ptr<sdbusplus::asio::dbus_interface> sensorIface;
+
+    double value = 0.0;
+};
+
+} // namespace stubs
diff --git a/tests/src/test_detached_timer.cpp b/tests/src/test_detached_timer.cpp
new file mode 100644
index 0000000..a5ff705
--- /dev/null
+++ b/tests/src/test_detached_timer.cpp
@@ -0,0 +1,34 @@
+#include "dbus_environment.hpp"
+#include "utils/detached_timer.hpp"
+
+#include <gmock/gmock.h>
+
+namespace utils
+{
+
+using namespace testing;
+using namespace std::chrono_literals;
+
+class TestDetachedTimer : public Test
+{
+  public:
+    uint32_t value = 0;
+};
+
+TEST_F(TestDetachedTimer, executesLambdaAfterTimeout)
+{
+    auto setPromise = DbusEnvironment::setPromise("timer");
+
+    makeDetachedTimer(DbusEnvironment::getIoc(), 100ms, [this, &setPromise] {
+        ++value;
+        setPromise();
+    });
+
+    auto elapsed = DbusEnvironment::measureTime(
+        [] { DbusEnvironment::waitForFuture("timer"); });
+
+    EXPECT_THAT(elapsed, AllOf(Ge(100ms), Lt(200ms)));
+    EXPECT_THAT(value, Eq(1u));
+}
+
+} // namespace utils
diff --git a/tests/src/test_sensor.cpp b/tests/src/test_sensor.cpp
new file mode 100644
index 0000000..c650831
--- /dev/null
+++ b/tests/src/test_sensor.cpp
@@ -0,0 +1,153 @@
+#include "dbus_environment.hpp"
+#include "mocks/sensor_listener_mock.hpp"
+#include "sensor.hpp"
+#include "sensor_cache.hpp"
+#include "stubs/dbus_sensor_object.hpp"
+#include "utils/sensor_id_eq.hpp"
+
+#include <sdbusplus/asio/property.hpp>
+
+#include <thread>
+
+#include <gmock/gmock.h>
+
+using namespace testing;
+using namespace std::chrono_literals;
+
+class TestSensor : public Test
+{
+  public:
+    void SetUp() override
+    {
+        sensorObject.setValue(42.7);
+    }
+
+    void TearDown() override
+    {
+        DbusEnvironment::synchronizeIoc();
+    }
+
+    void
+        registerForUpdates(std::shared_ptr<interfaces::SensorListener> listener)
+    {
+        DbusEnvironment::synchronizedPost(
+            [this, listener] { sut->registerForUpdates(listener); });
+    }
+
+    std::chrono::milliseconds notifiesInGivenIntervalAfterSchedule(
+        std::chrono::milliseconds interval);
+
+    stubs::DbusSensorObject sensorObject{DbusEnvironment::getIoc(),
+                                         DbusEnvironment::getBus(),
+                                         DbusEnvironment::getObjServer()};
+
+    SensorCache sensorCache;
+    uint64_t timestamp = std::time(0);
+    std::shared_ptr<Sensor> sut = sensorCache.makeSensor<Sensor>(
+        DbusEnvironment::serviceName(), sensorObject.path(),
+        DbusEnvironment::getIoc(), DbusEnvironment::getBus());
+    std::shared_ptr<SensorListenerMock> listenerMock =
+        std::make_shared<StrictMock<SensorListenerMock>>();
+    std::shared_ptr<SensorListenerMock> listenerMock2 =
+        std::make_shared<StrictMock<SensorListenerMock>>();
+};
+
+TEST_F(TestSensor, createsCorretlyViaSensorCache)
+{
+    ASSERT_THAT(sut->id(),
+                sensorIdEq(Sensor::Id("Sensor", DbusEnvironment::serviceName(),
+                                      sensorObject.path())));
+}
+
+TEST_F(TestSensor, notifiesWithValueAfterRegister)
+{
+    EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .WillOnce(Invoke(DbusEnvironment::setPromise("async_read")));
+
+    registerForUpdates(listenerMock);
+
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("async_read"));
+}
+
+TEST_F(TestSensor, notifiesOnceWithValueAfterRegister)
+{
+    EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .WillOnce(Invoke(DbusEnvironment::setPromise("async_read")));
+    EXPECT_CALL(*listenerMock2, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .WillOnce(Invoke(DbusEnvironment::setPromise("async_read2")));
+
+    DbusEnvironment::synchronizedPost([this] {
+        sut->registerForUpdates(listenerMock);
+        sut->registerForUpdates(listenerMock2);
+    });
+
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("async_read"));
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("async_read2"));
+}
+
+class TestSensorNotification : public TestSensor
+{
+  public:
+    void SetUp() override
+    {
+        EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp), 0.))
+            .WillOnce(Invoke(DbusEnvironment::setPromise("async_read")));
+
+        registerForUpdates(listenerMock);
+
+        ASSERT_TRUE(DbusEnvironment::waitForFuture("async_read"));
+    }
+
+    std::shared_ptr<SensorListenerMock> listenerMock2 =
+        std::make_shared<StrictMock<SensorListenerMock>>();
+};
+
+TEST_F(TestSensorNotification, notifiesListenerWithValueWhenChangeOccurs)
+{
+    EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .WillOnce(Invoke(DbusEnvironment::setPromise("notify")));
+
+    sensorObject.setValue(42.7);
+
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("notify"));
+}
+
+TEST_F(TestSensorNotification, notifiesListenerWithValueWhenNoChangeOccurs)
+{
+    Sequence seq;
+
+    EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .InSequence(seq);
+    EXPECT_CALL(*listenerMock, sensorUpdated(Ref(*sut), Ge(timestamp)))
+        .InSequence(seq)
+        .WillOnce(Invoke(DbusEnvironment::setPromise("notify")));
+
+    sensorObject.setValue(42.7);
+    sensorObject.setValue(42.7);
+
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("notify"));
+}
+
+TEST_F(TestSensorNotification, doesntNotifyExpiredListener)
+{
+    Sequence seq;
+    EXPECT_CALL(*listenerMock2, sensorUpdated(Ref(*sut), Ge(timestamp), 0.))
+        .InSequence(seq);
+    EXPECT_CALL(*listenerMock2, sensorUpdated(Ref(*sut), Ge(timestamp), 42.7))
+        .InSequence(seq)
+        .WillOnce(Invoke(DbusEnvironment::setPromise("notify")));
+
+    registerForUpdates(listenerMock2);
+    listenerMock = nullptr;
+
+    sensorObject.setValue(42.7);
+
+    ASSERT_TRUE(DbusEnvironment::waitForFuture("notify"));
+}
+
+TEST_F(TestSensorNotification, notifiesWithValueDuringRegister)
+{
+    EXPECT_CALL(*listenerMock2, sensorUpdated(Ref(*sut), Ge(timestamp), 0.));
+
+    registerForUpdates(listenerMock2);
+}
diff --git a/tests/src/test_sensor_cache.cpp b/tests/src/test_sensor_cache.cpp
index 5be9a0d..a3831dc 100644
--- a/tests/src/test_sensor_cache.cpp
+++ b/tests/src/test_sensor_cache.cpp
@@ -1,5 +1,6 @@
 #include "mocks/sensor_mock.hpp"
 #include "sensor_cache.hpp"
+#include "utils/sensor_id_eq.hpp"
 
 #include <initializer_list>
 
@@ -13,13 +14,6 @@
     SensorCache sut;
 };
 
-auto sensorIdEq(interfaces::Sensor::Id id)
-{
-    return AllOf(Field(&interfaces::Sensor::Id::type, Eq(id.type)),
-                 Field(&interfaces::Sensor::Id::service, Eq(id.service)),
-                 Field(&interfaces::Sensor::Id::path, Eq(id.path)));
-}
-
 struct IdParam
 {
     IdParam() = default;
diff --git a/tests/src/test_unique_call.cpp b/tests/src/test_unique_call.cpp
new file mode 100644
index 0000000..876edd1
--- /dev/null
+++ b/tests/src/test_unique_call.cpp
@@ -0,0 +1,51 @@
+#include "utils/unique_call.hpp"
+
+#include <gmock/gmock.h>
+
+namespace utils
+{
+
+using namespace testing;
+
+class TestUniqueCall : public Test
+{
+  public:
+    void uniqueCallIncrementCounter()
+    {
+        uniqueCall1([this](auto context) { ++counter; });
+    }
+
+    void uniqueCallWhileUniqueCallIsActiveIncrementCounter()
+    {
+        uniqueCall2([this](auto context) {
+            ++counter;
+            uniqueCallWhileUniqueCallIsActiveIncrementCounter();
+        });
+    }
+
+    UniqueCall uniqueCall1;
+    UniqueCall uniqueCall2;
+    uint32_t counter = 0u;
+};
+
+TEST_F(TestUniqueCall, shouldExecuteNormally)
+{
+    for (size_t i = 0; i < 3u; ++i)
+    {
+        uniqueCallIncrementCounter();
+    }
+
+    ASSERT_THAT(counter, Eq(3u));
+}
+
+TEST_F(TestUniqueCall, shouldNotExecuteWhenPreviousExecutionIsStillActive)
+{
+    for (size_t i = 0; i < 3u; ++i)
+    {
+        uniqueCallWhileUniqueCallIsActiveIncrementCounter();
+    }
+
+    ASSERT_THAT(counter, Eq(3u));
+}
+
+} // namespace utils
diff --git a/tests/src/utils/sensor_id_eq.hpp b/tests/src/utils/sensor_id_eq.hpp
new file mode 100644
index 0000000..f952504
--- /dev/null
+++ b/tests/src/utils/sensor_id_eq.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "interfaces/sensor.hpp"
+
+#include <gmock/gmock.h>
+
+inline auto sensorIdEq(interfaces::Sensor::Id id)
+{
+    using namespace testing;
+
+    return AllOf(Field(&interfaces::Sensor::Id::type, Eq(id.type)),
+                 Field(&interfaces::Sensor::Id::service, Eq(id.service)),
+                 Field(&interfaces::Sensor::Id::path, Eq(id.path)));
+}