diff --git a/Ed25519 Tests/Ed25519 Tests.csproj b/Ed25519 Tests/Ed25519 Tests.csproj
new file mode 100644
index 0000000..57d11d6
--- /dev/null
+++ b/Ed25519 Tests/Ed25519 Tests.csproj	
@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <RootNamespace>Ed25519_Tests</RootNamespace>
+
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="nunit" Version="3.12.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="3.15.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Ed25519\Ed25519.csproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/Ed25519 Tests/SignerTests.cs b/Ed25519 Tests/SignerTests.cs
new file mode 100644
index 0000000..91c6e97
--- /dev/null
+++ b/Ed25519 Tests/SignerTests.cs	
@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Ed25519;
+using NUnit.Framework;
+using NUnit.Framework.Constraints;
+
+namespace Ed25519_Tests
+{
+    public sealed class SignerTests
+    {
+        [Test]
+        public void TestSigner01()
+        {
+            var message = Encoding.UTF8.GetBytes("This is a test message.");
+            var publicKey = Encoding.ASCII.GetBytes("01365464163464646464164641634160"); // 32 bytes
+            var privateKey = Encoding.ASCII.GetBytes("Secret key");
+
+            var signature = Signer.Sign(message, privateKey, publicKey);
+
+            Assert.That(signature.Length, Is.EqualTo(64));
+        }
+
+        [Test]
+        public void TestSigner02()
+        {
+            var message = Encoding.UTF8.GetBytes("This is a test message.");
+            var publicKey = Encoding.ASCII.GetBytes("0136546416346464646416464163416"); // 31 bytes
+            var privateKey = Encoding.ASCII.GetBytes("Secret key");
+
+            Assert.That(() => Signer.Sign(message, privateKey, publicKey), Throws.ArgumentException); // Public key is too short
+        }
+
+        [Test]
+        public void TestSigner03()
+        {
+            var message = Encoding.UTF8.GetBytes("This is a test message.");
+            var publicKey = Encoding.ASCII.GetBytes("01365464163464646464164641634160"); // 32 bytes
+            var privateKey = Encoding.ASCII.GetBytes("Secret key");
+
+            var signature = Signer.Sign(message, privateKey, publicKey);
+            var validationResult = Signer.Validate(signature, message, publicKey);
+
+            Assert.That(validationResult, Is.True);
+        }
+    }
+}
diff --git a/Ed25519.sln b/Ed25519.sln
index 144c19e..ed1a8ed 100644
--- a/Ed25519.sln
+++ b/Ed25519.sln
@@ -3,7 +3,9 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 16
 VisualStudioVersion = 16.0.29613.14
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ed25519", "Ed25519\Ed25519.csproj", "{A36D2E95-E99A-4CB4-B735-417BAE007BC7}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Ed25519", "Ed25519\Ed25519.csproj", "{A36D2E95-E99A-4CB4-B735-417BAE007BC7}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ed25519 Tests", "Ed25519 Tests\Ed25519 Tests.csproj", "{7CF58545-8CB8-4B23-82DF-D1E71679151C}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -15,6 +17,10 @@ Global
 		{A36D2E95-E99A-4CB4-B735-417BAE007BC7}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A36D2E95-E99A-4CB4-B735-417BAE007BC7}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{A36D2E95-E99A-4CB4-B735-417BAE007BC7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{7CF58545-8CB8-4B23-82DF-D1E71679151C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7CF58545-8CB8-4B23-82DF-D1E71679151C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7CF58545-8CB8-4B23-82DF-D1E71679151C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7CF58545-8CB8-4B23-82DF-D1E71679151C}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE