ExampleRequest.cs

using Gravyframe.Service.Messages;

namespace Gravyframe.Service.Example
{
  public class ExampleRequest : Request
  {
  }
}

ExampleResponse.cs

using Gravyframe.Service.Messages;

namespace Gravyframe.Service.Example
{
  public class ExampleResponse : Response
  {
  }
}

ExampleService.cs

using System;
using System.Collections.Generic;

namespace Gravyframe.Service.Example
{
  public class ExampleService : Service<ExampleRequest, ExampleResponse, ExampleService.NullExampleRequestException>
  {
    public ExampleService(IEnumerable<ResponseHydrator<ExampleRequest, ExampleResponse>> responseHydratationTasks)
    : base(responseHydratationTasks)
    {
    }
    
    [Serializable]
    public class NullExampleRequestException : NullRequestException
    {
    }
  }
}

ExampleServiceTests.cs

using System.Collections.Generic;
using Gravyframe.Service.Example;

namespace Gravyframe.Service.Tests
{
  public class ExampleServiceTests : ServiceTests<ExampleRequest, ExampleResponse, ExampleService, ExampleService.NullExampleRequestException>
  {
    public IEnumerable<ResponseHydrator<ExampleRequest, ExampleResponse>> ResponseHydratationTasks;
    
    protected override void ServiceSetUp()
    {
      ResponseHydratationTasks = new List<ResponseHydrator<ExampleRequest, ExampleResponse>>();
      Sut = new ExampleService(ResponseHydratationTasks);
    }
  }
}

ServiceTests.cs

using Gravyframe.Service.Messages;
using NUnit.Framework;
namespace Gravyframe.Service.Tests
{
  [TestFixture]
  public abstract class ServiceTests<TRequest, TResponce, TService, TNullRequestException>
    where TResponce : Response, new()
    where TRequest : Request, new()
    where TService : Service<TRequest, TResponce, TNullRequestException>
    where TNullRequestException : Service<TRequest, TResponce,TNullRequestException>.NullRequestException, new()
    {
      public TService Sut;
      [SetUp]
      protected void SetUp()
      {
        ServiceSetUp();
      }

      protected abstract void ServiceSetUp();

      [Test]
      public void CanCreateTService()
      {
          // Assert
          Assert.IsNotNull(Sut);
      }

      [Test]
      public void IsAssignableFromTService()
      {
          // Assert 
          Assert.IsInstanceOf<Service<TRequest, TResponce, TNullRequestException>>(Sut);
      }

      [Test]
      public void WhenRequestIsNullTNullRequestThrown()
      {
          // Assert
          Assert.Throws<TNullRequestException>(() => Sut.Get(null));
      }

      [Test]
      public void 
      WhenTRequestInNotNullTNullRequestExceptionNotThrown()
      {
          // Assign
          var request = new TRequest();

          // Assert
          Assert.DoesNotThrow(() => Sut.Get(request));
      }

      [Test]
      public void WhenTRequestIsNotNullTResponceNotNull()
      {
          // Assign
          var request = new TRequest();

          // Act
          var responce = Sut.Get(request);

          // Assert
          Assert.IsNotNull(responce);
      }
    }
}