feat: add JoeAppEngine OPC UA nodes, fix DCL auto-reconnect and quality push

- Add JoeAppEngine folder to OPC UA nodes.json (BTCS, AlarmCntsBySeverity, Scheduler/ScanTime)
- Fix DataConnectionActor: capture Self in PreStart for use from non-actor threads,
  preventing Self.Tell failure in Disconnected event handler
- Implement InstanceActor.HandleConnectionQualityChanged to mark attributes Bad on disconnect
- Fix LmxFakeProxy TagMapper to serialize arrays as JSON instead of "System.Int32[]"
- Allow DataType and DataSourceReference updates in TemplateService.UpdateAttributeAsync
- Update test_infra_opcua.md with JoeAppEngine documentation

tests/ScadaLink.CentralUI.Tests/ComponentRenderingTests.cs

@@ -0,0 +1,83 @@
+using System.Security.Claims;
+using Bunit;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Components.Authorization;
+using Microsoft.Extensions.DependencyInjection;
+using ScadaLink.CentralUI.Components.Pages;
+
+namespace ScadaLink.CentralUI.Tests;
+
+/// <summary>
+/// bUnit rendering tests for CentralUI Blazor components.
+/// Verifies that pages render their expected markup structure.
+/// </summary>
+public class ComponentRenderingTests : BunitContext
+{
+    [Fact]
+    public void LoginPage_RendersForm_WithUsernameAndPasswordFields()
+    {
+        var cut = Render<Login>();
+
+        // Verify the form action
+        var form = cut.Find("form");
+        Assert.Equal("/auth/login", form.GetAttribute("action"));
+
+        // Verify username field
+        var usernameInput = cut.Find("input#username");
+        Assert.Equal("text", usernameInput.GetAttribute("type"));
+        Assert.Equal("username", usernameInput.GetAttribute("name"));
+
+        // Verify password field
+        var passwordInput = cut.Find("input#password");
+        Assert.Equal("password", passwordInput.GetAttribute("type"));
+        Assert.Equal("password", passwordInput.GetAttribute("name"));
+
+        // Verify submit button
+        var submitButton = cut.Find("button[type='submit']");
+        Assert.Contains("Sign In", submitButton.TextContent);
+    }
+
+    [Fact]
+    public void LoginPage_WithoutError_DoesNotRenderAlert()
+    {
+        var cut = Render<Login>();
+
+        Assert.Throws<Bunit.ElementNotFoundException>(() => cut.Find("div.alert.alert-danger"));
+    }
+
+    [Fact]
+    public void Dashboard_RequiresAuthorizeAttribute()
+    {
+        var authorizeAttrs = typeof(Dashboard)
+            .GetCustomAttributes(typeof(AuthorizeAttribute), true);
+        Assert.NotEmpty(authorizeAttrs);
+    }
+
+    [Fact]
+    public void TemplateEditor_RequiresDesignPolicy()
+    {
+        var authorizeAttrs = typeof(ScadaLink.CentralUI.Components.Pages.Design.Templates)
+            .GetCustomAttributes(typeof(AuthorizeAttribute), true);
+        Assert.NotEmpty(authorizeAttrs);
+
+        var attr = (AuthorizeAttribute)authorizeAttrs[0];
+        Assert.Equal("RequireDesign", attr.Policy);
+    }
+
+    [Fact]
+    public void LoginPage_RendersLdapCredentialHint()
+    {
+        var cut = Render<Login>();
+
+        Assert.Contains("LDAP credentials", cut.Markup);
+    }
+
+    [Fact]
+    public void LoginPage_RendersScadaLinkTitle()
+    {
+        var cut = Render<Login>();
+
+        var title = cut.Find("h4.card-title");
+        Assert.Equal("ScadaLink", title.TextContent);
+    }
+}

tests/ScadaLink.CentralUI.Tests/ScadaLink.CentralUI.Tests.csproj

@@ -9,8 +9,10 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="bunit" Version="2.0.33-preview" />
     <PackageReference Include="coverlet.collector" Version="6.0.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="NSubstitute" Version="5.3.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
   </ItemGroup>
@@ -19,6 +21,10 @@
     <Using Include="Xunit" />
   </ItemGroup>
 
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="../../src/ScadaLink.CentralUI/ScadaLink.CentralUI.csproj" />
   </ItemGroup>