diff --git a/include/DataStorageClient.h b/include/DataStorageClient.h
index 16f5b06..2f79813 100644
--- a/include/DataStorageClient.h
+++ b/include/DataStorageClient.h
@@ -15,20 +15,35 @@ namespace DataStorage {
 
 class DataStorageClientImpl;
 
-class DataStorageClient
+class IDataStorageClient
+{
+public:
+	virtual ~IDataStorageClient() {}
+
+public:
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, int value) = 0;
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, double value) = 0;
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, const std::string& value) = 0;
+
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, int value) = 0;
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, double value) = 0;
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, const std::string& value) = 0;
+};
+
+class DataStorageClient : public IDataStorageClient
 {
 public:
 	DataStorageClient(const std::shared_ptr<MySQL::MySQLClient>& pMySQLClient, const std::string& table);
 	~DataStorageClient();
 
 public:
-	void LogValue(int deviceId, const std::string& dataName, int timestamp, int value);
-	void LogValue(int deviceId, const std::string& dataName, int timestamp, double value);
-	void LogValue(int deviceId, const std::string& dataName, int timestamp, const std::string& value);
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, int value);
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, double value);
+	virtual void LogValue(int deviceId, const std::string& dataName, int timestamp, const std::string& value);
 
-	void LogValueTimed(int deviceId, const std::string& dataName, int value);
-	void LogValueTimed(int deviceId, const std::string& dataName, double value);
-	void LogValueTimed(int deviceId, const std::string& dataName, const std::string& value);
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, int value);
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, double value);
+	virtual void LogValueTimed(int deviceId, const std::string& dataName, const std::string& value);
 
 public:
 	void MetronomeCallback();