Add unit tests for KubernetesCluster, Tenant, ServiceInstance, and RegisterClusterHandler

- Implement tests for KubernetesCluster including registration, connectivity status, and error handling.
- Create tests for Tenant creation, member management, and status changes.
- Add tests for ServiceInstance provisioning and state management.
- Introduce RegisterClusterHandler tests to validate registration requests and error scenarios.
- Set up project files for new test projects with necessary dependencies.

tests/EntKube.Clusters.Tests/Features/RegisterClusterHandlerTests.cs

@@ -0,0 +1,74 @@
+using EntKube.Clusters.Domain;
+using EntKube.Clusters.Features.RegisterCluster;
+using EntKube.Clusters.Infrastructure;
+using EntKube.SharedKernel.Domain;
+using FluentAssertions;
+
+namespace EntKube.Clusters.Tests.Features;
+
+public class RegisterClusterHandlerTests
+{
+    private readonly RegisterClusterHandler handler;
+    private readonly InMemoryClusterRepository repository;
+
+    public RegisterClusterHandlerTests()
+    {
+        repository = new InMemoryClusterRepository();
+        handler = new RegisterClusterHandler(repository);
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithValidRequest_ReturnsSuccessWithClusterId()
+    {
+        // Arrange — A valid registration request with all required fields.
+
+        RegisterClusterRequest request = new("production-eu", "https://k8s.example.com:6443", "secret-ref");
+
+        // Act
+
+        Result<Guid> result = await handler.HandleAsync(request);
+
+        // Assert — The handler should succeed and the cluster should be persisted.
+
+        result.IsSuccess.Should().BeTrue();
+        result.Value.Should().NotBe(Guid.Empty);
+
+        KubernetesCluster? persisted = await repository.GetByIdAsync(result.Value!);
+        persisted.Should().NotBeNull();
+        persisted!.Name.Should().Be("production-eu");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithEmptyName_ReturnsFailure()
+    {
+        // Arrange — Missing cluster name.
+
+        RegisterClusterRequest request = new("", "https://k8s.example.com:6443", null);
+
+        // Act
+
+        Result<Guid> result = await handler.HandleAsync(request);
+
+        // Assert
+
+        result.IsFailure.Should().BeTrue();
+        result.Error.Should().Contain("name");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithEmptyApiUrl_ReturnsFailure()
+    {
+        // Arrange — Missing API server URL.
+
+        RegisterClusterRequest request = new("my-cluster", "", null);
+
+        // Act
+
+        Result<Guid> result = await handler.HandleAsync(request);
+
+        // Assert
+
+        result.IsFailure.Should().BeTrue();
+        result.Error.Should().Contain("API server URL");
+    }
+}