refactor(HistoryTests): Vereinfachung von HistoryTests durch direkte Einbindung von IMediator

- Entfernen der benutzerdefinierten Hilfsmethode Send<T>
 - Einführung der Mediator-Eigenschaft, die aus dem DI-Container aufgelöst wird
 - Ersetzen aller Send(request)-Aufrufe durch Mediator.Send(request)
 - Reduzierung unnötiger Indirektionen, wodurch Tests übersichtlicher und leichter lesbar werden

EnvelopeGenerator.Tests.Application/HistoryTests.cs

@@ -16,7 +16,7 @@ public class HistoryTests
 {
     private IHost _host;
 
-    private IServiceProvider Provider => _host.Services;
+    private IMediator Mediator => _host.Services.GetRequiredService<IMediator>();
 
     [SetUp]
     public void Setup()
@@ -50,12 +50,6 @@ public class HistoryTests
         _host.Dispose();
     }
 
-    private async Task<TResponse> Send<TResponse>(IRequest<TResponse> request)
-    {
-        var mediator = Provider.GetRequiredService<IMediator>();
-        return await mediator.Send(request);
-    }
-
     [Test]
     public async Task CreateHistory_And_ReadHistory_Should_Work()
     {
@@ -69,14 +63,14 @@ public class HistoryTests
         };
 
         // Act
-        var id = await Send(createCmd);
+        var id = await Mediator.Send(createCmd);
 
         // Assert
         Assert.That(id, Is.Not.Null);
 
         // ReadHistory sorgusu
         var query = new ReadHistoryQuery(1);
-        var result = await Send(query);
+        var result = await Mediator.Send(query);
 
         Assert.That(result, Is.Not.Empty);
     }
@@ -99,11 +93,11 @@ public class HistoryTests
             Status = Constants.EnvelopeStatus.EnvelopePartlySigned
         };
 
-        await Send(createCmd1);
-        await Send(createCmd2);
+        await Mediator.Send(createCmd1);
+        await Mediator.Send(createCmd2);
 
         // Act
-        var result = await Send(new ReadHistoryQuery(2, Constants.EnvelopeStatus.EnvelopePartlySigned));
+        var result = await Mediator.Send(new ReadHistoryQuery(2, Constants.EnvelopeStatus.EnvelopePartlySigned));
 
         // Assert
         Assert.That(result, Has.Exactly(1).Items);
@@ -115,7 +109,7 @@ public class HistoryTests
     public async Task ReadHistory_Should_Return_Empty_When_No_Record()
     {
         // Act
-        var result = await Send(new ReadHistoryQuery(999));
+        var result = await Mediator.Send(new ReadHistoryQuery(999));
 
         // Assert
         Assert.That(result, Is.Empty);