diff --git a/Core/Cache/ICacheStorage.cs b/Core/Cache/ICacheStorage.cs
index 016f554..0983354 100644
--- a/Core/Cache/ICacheStorage.cs
+++ b/Core/Cache/ICacheStorage.cs
@@ -4,7 +4,7 @@ namespace Kruzya.TelegramBot.Core.Cache
 {
     public interface ICacheStorage<TKey, TValue>
     {
-        public bool TryGetValue(TKey key, ref TValue value);
+        public bool TryGetValue(TKey key, out TValue value);
         public void SetValue(TKey key, TValue value, int timeToLive);
     }
 }
\ No newline at end of file
diff --git a/Core/Cache/MemoryCache.cs b/Core/Cache/MemoryCache.cs
index b4afc69..baf063f 100644
--- a/Core/Cache/MemoryCache.cs
+++ b/Core/Cache/MemoryCache.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
+using SQLitePCL;
 
 namespace Kruzya.TelegramBot.Core.Cache
 {
@@ -47,9 +48,10 @@ namespace Kruzya.TelegramBot.Core.Cache
             _defaultTtl = defaultTtl;
         }
         
-        public bool TryGetValue(TKey key, ref TValue value)
+        public bool TryGetValue(TKey key, out TValue value)
         {
-            if (dict.ContainsKey(key))
+            value = default;
+            if (!dict.ContainsKey(key))
             {
                 return false;
             }
diff --git a/Kruzya.TelegramBot.sln b/Kruzya.TelegramBot.sln
index 4e5a92d..05b2821 100644
--- a/Kruzya.TelegramBot.sln
+++ b/Kruzya.TelegramBot.sln
@@ -8,6 +8,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CombotAntiSpam", "modules\C
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RichSiteSummary", "modules\RichSiteSummary\RichSiteSummary.csproj", "{C50D64C3-204B-4B58-927B-C8D759787252}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Tests", "tests\Tests.csproj", "{5C62CA70-F270-4029-953E-458623C31A3B}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -26,6 +28,10 @@ Global
 		{C50D64C3-204B-4B58-927B-C8D759787252}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{C50D64C3-204B-4B58-927B-C8D759787252}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{C50D64C3-204B-4B58-927B-C8D759787252}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5C62CA70-F270-4029-953E-458623C31A3B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5C62CA70-F270-4029-953E-458623C31A3B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5C62CA70-F270-4029-953E-458623C31A3B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5C62CA70-F270-4029-953E-458623C31A3B}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{F1E1FBB7-ABA4-4304-9A42-D4975822B002} = {C7821F15-DEDD-474F-A575-A296D4B58F10}
diff --git a/tests/MemoryCache.cs b/tests/MemoryCache.cs
new file mode 100644
index 0000000..5c3cb2d
--- /dev/null
+++ b/tests/MemoryCache.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Kruzya.TelegramBot.Core.Cache;
+using NUnit.Framework;
+
+namespace Kruzya.TelegramBot.Core.Tests
+{
+    public class MemoryCache
+    {
+        [Test]
+        public void GetSetItem()
+        {
+            var cache = new MemoryCache<string, int>();
+
+            int id;
+            Assert.IsFalse(cache.TryGetValue("user", out id), "GetValue() returned something");
+            
+            id = 5;
+            cache.SetValue("user", id);
+
+            id = 10;
+            Assert.IsTrue(cache.TryGetValue("user", out id), "GetValue() doesn't returned any value");
+            Assert.IsTrue(id == 5, "GetValue() returned don't expected value");
+        }
+
+        [Test]
+        public void TimeToLive()
+        {
+            var cache = new MemoryCache<string, int>();
+            cache.SetValue("user", 5, 1);
+            cache.SetValue("admin", 10, 2);
+            cache.SetValue("manager", 15, Timeout.Infinite);
+
+            int id;
+            Thread.Sleep(TimeSpan.FromSeconds(1));
+            Assert.IsFalse(cache.TryGetValue("user", out id), "GetValue() returned expired entry (user).");
+            Assert.IsTrue(cache.TryGetValue("admin", out id), "GetValue() doesn't returned live entry.");
+            Assert.IsTrue(id == 10, "GetValue() returned unexpected entry.");
+            
+            Thread.Sleep(TimeSpan.FromSeconds(1));
+            Assert.IsFalse(cache.TryGetValue("admin", out id), "GetValue() returned expired entry (admin).");
+            Assert.IsTrue(cache.TryGetValue("manager", out id), "GetValue() doesn't returned live entry.");
+            Assert.IsTrue(id == 15, "GetValue() returned unexpected entry.");
+        }
+    }
+}
\ No newline at end of file
diff --git a/tests/Tests.csproj b/tests/Tests.csproj
new file mode 100644
index 0000000..fab280a
--- /dev/null
+++ b/tests/Tests.csproj
@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>netcoreapp3.1</TargetFramework>
+
+        <IsPackable>false</IsPackable>
+
+        <AssemblyName>TelegramBot.Test</AssemblyName>
+
+        <RootNamespace>Kruzya.TelegramBot.Core.Tests</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="nunit" Version="3.12.0" />
+        <PackageReference Include="NUnit3TestAdapter" Version="3.15.1" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\Core\Core.csproj" />
+    </ItemGroup>
+
+</Project>