too much for one commit

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

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+using EntKube.Clusters.Domain;
+using EntKube.Clusters.Features.AdoptCluster;
+using EntKube.Clusters.Features.InstallPrometheus;
+using EntKube.Clusters.Infrastructure;
+using EntKube.SharedKernel.Domain;
+using FluentAssertions;
+
+namespace EntKube.Clusters.Tests.Features;
+
+public class InstallPrometheusHandlerTests
+{
+    private readonly InMemoryClusterRepository repository;
+
+    public InstallPrometheusHandlerTests()
+    {
+        repository = new InMemoryClusterRepository();
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithValidCluster_InstallsAndReturnsSuccess()
+    {
+        // Arrange — A cluster with no Prometheus. The user wants to install
+        // kube-prometheus-stack via Helm with a production configuration.
+
+        KubernetesCluster cluster = KubernetesCluster.Register(
+            "fresh-cluster",
+            "https://k8s.example.com:6443",
+            "kubeconfig-data",
+            Guid.NewGuid(),
+            "prod-ctx", Guid.NewGuid());
+
+        await repository.AddAsync(cluster);
+
+        FakeMonitoringInstaller installer = new(success: true);
+        InstallPrometheusHandler handler = new(repository, new List<IComponentInstaller> { installer });
+
+        // Act — Install Prometheus on the cluster.
+
+        Result<PrometheusInstallResult> result = await handler.HandleAsync(
+            new InstallPrometheusRequest(cluster.Id, "monitoring"));
+
+        // Assert — The install should succeed and the cluster should have
+        // the Prometheus endpoint stored.
+
+        result.IsSuccess.Should().BeTrue();
+        result.Value!.Namespace.Should().Be("monitoring");
+        result.Value.ReleaseName.Should().Be("kube-prometheus-stack");
+
+        KubernetesCluster? updated = await repository.GetByIdAsync(cluster.Id);
+        updated!.PrometheusEndpoints.Should().HaveCount(1);
+        updated.PrometheusEndpoints[0].Namespace.Should().Be("monitoring");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithNonExistentCluster_ReturnsFailure()
+    {
+        // Arrange
+
+        FakeMonitoringInstaller installer = new(success: true);
+        InstallPrometheusHandler handler = new(repository, new List<IComponentInstaller> { installer });
+
+        // Act
+
+        Result<PrometheusInstallResult> result = await handler.HandleAsync(
+            new InstallPrometheusRequest(Guid.NewGuid(), "monitoring"));
+
+        // Assert
+
+        result.IsFailure.Should().BeTrue();
+        result.Error.Should().Contain("not found");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WhenHelmFails_ReturnsFailure()
+    {
+        // Arrange — Helm install fails (e.g., no connectivity, insufficient permissions).
+
+        KubernetesCluster cluster = KubernetesCluster.Register(
+            "broken-cluster",
+            "https://broken.example.com:6443",
+            "kubeconfig-data",
+            Guid.NewGuid(),
+            "ctx", Guid.NewGuid());
+
+        await repository.AddAsync(cluster);
+
+        FakeMonitoringInstaller installer = new(success: false, errorMessage: "Tiller not available");
+        InstallPrometheusHandler handler = new(repository, new List<IComponentInstaller> { installer });
+
+        // Act
+
+        Result<PrometheusInstallResult> result = await handler.HandleAsync(
+            new InstallPrometheusRequest(cluster.Id, "monitoring"));
+
+        // Assert
+
+        result.IsFailure.Should().BeTrue();
+        result.Error.Should().Contain("Tiller not available");
+    }
+
+    [Fact]
+    public async Task HandleAsync_DefaultsToMonitoringNamespace()
+    {
+        // Arrange — The request doesn't specify a namespace, so it should
+        // default to "monitoring".
+
+        KubernetesCluster cluster = KubernetesCluster.Register(
+            "default-ns-cluster",
+            "https://k8s.example.com:6443",
+            "kubeconfig-data",
+            Guid.NewGuid(),
+            "ctx", Guid.NewGuid());
+
+        await repository.AddAsync(cluster);
+
+        FakeMonitoringInstaller installer = new(success: true);
+        InstallPrometheusHandler handler = new(repository, new List<IComponentInstaller> { installer });
+
+        // Act
+
+        Result<PrometheusInstallResult> result = await handler.HandleAsync(
+            new InstallPrometheusRequest(cluster.Id, null));
+
+        // Assert — Should install to "monitoring" namespace.
+
+        result.IsSuccess.Should().BeTrue();
+        result.Value!.Namespace.Should().Be("monitoring");
+    }
+}
+
+/// <summary>
+/// Test double for the monitoring component installer. Returns pre-configured results
+/// without actually running helm commands.
+/// </summary>
+public class FakeMonitoringInstaller : IComponentInstaller
+{
+    private readonly bool success;
+    private readonly string? errorMessage;
+
+    public string ComponentName => "monitoring";
+
+    public FakeMonitoringInstaller(bool success, string? errorMessage = null)
+    {
+        this.success = success;
+        this.errorMessage = errorMessage;
+    }
+
+    public Task<InstallResult> InstallAsync(KubernetesCluster cluster, ComponentInstallOptions options, CancellationToken ct = default)
+    {
+        if (success)
+        {
+            return Task.FromResult(new InstallResult(
+                true,
+                ComponentName,
+                "kube-prometheus-stack installed",
+                new List<string> { "Helm install succeeded" }));
+        }
+
+        return Task.FromResult(new InstallResult(
+            false,
+            ComponentName,
+            errorMessage ?? "Install failed",
+            new List<string> { $"Error: {errorMessage}" }));
+    }
+
+    public Task<InstallResult> ConfigureAsync(KubernetesCluster cluster, ComponentConfiguration configuration, CancellationToken ct = default)
+    {
+        return Task.FromResult(new InstallResult(
+            true,
+            ComponentName,
+            "Monitoring reconfigured",
+            new List<string> { "Configuration applied" }));
+    }
+}