Phase 2 WP-1–13+23: Template Engine CRUD, composition, overrides, locking, collision detection, acyclicity

- WP-23: ITemplateEngineRepository full EF Core implementation
- WP-1: Template CRUD with deletion constraints (instances, children, compositions)
- WP-2–4: Attribute, alarm, script definitions with lock flags and override granularity
- WP-5: Shared script CRUD with syntax validation
- WP-6–7: Composition with recursive nesting and canonical naming
- WP-8–11: Override granularity, locking rules, inheritance/composition scope
- WP-12: Naming collision detection on canonical names (recursive)
- WP-13: Graph acyclicity (inheritance + composition cycles)
Core services: TemplateService, SharedScriptService, TemplateResolver,
LockEnforcer, CollisionDetector, CycleDetector. 358 tests pass.

tests/ScadaLink.TemplateEngine.Tests/Services/AreaServiceTests.cs

@@ -0,0 +1,144 @@
+using Moq;
+using ScadaLink.Commons.Entities.Instances;
+using ScadaLink.Commons.Interfaces.Repositories;
+using ScadaLink.Commons.Interfaces.Services;
+using ScadaLink.TemplateEngine.Services;
+
+namespace ScadaLink.TemplateEngine.Tests.Services;
+
+public class AreaServiceTests
+{
+    private readonly Mock<ITemplateEngineRepository> _repoMock = new();
+    private readonly Mock<IAuditService> _auditMock = new();
+    private readonly AreaService _sut;
+
+    public AreaServiceTests()
+    {
+        _sut = new AreaService(_repoMock.Object, _auditMock.Object);
+    }
+
+    [Fact]
+    public async Task CreateArea_ValidInput_ReturnsSuccess()
+    {
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area>());
+        _repoMock.Setup(r => r.SaveChangesAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(1);
+
+        var result = await _sut.CreateAreaAsync("Building A", 1, null, "admin");
+
+        Assert.True(result.IsSuccess);
+        Assert.Equal("Building A", result.Value.Name);
+        Assert.Equal(1, result.Value.SiteId);
+    }
+
+    [Fact]
+    public async Task CreateArea_DuplicateName_ReturnsFailure()
+    {
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area>
+            {
+                new("Building A") { Id = 1, SiteId = 1, ParentAreaId = null }
+            });
+
+        var result = await _sut.CreateAreaAsync("Building A", 1, null, "admin");
+
+        Assert.True(result.IsFailure);
+        Assert.Contains("already exists", result.Error);
+    }
+
+    [Fact]
+    public async Task CreateArea_WithParent_ValidatesParentBelongsToSite()
+    {
+        _repoMock.Setup(r => r.GetAreaByIdAsync(5, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Area("Parent") { Id = 5, SiteId = 99 }); // Different site!
+
+        var result = await _sut.CreateAreaAsync("Child", 1, 5, "admin");
+
+        Assert.True(result.IsFailure);
+        Assert.Contains("does not belong", result.Error);
+    }
+
+    [Fact]
+    public async Task DeleteArea_WithAssignedInstances_ReturnsFailure()
+    {
+        _repoMock.Setup(r => r.GetAreaByIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Area("Building A") { Id = 1, SiteId = 1 });
+        _repoMock.Setup(r => r.GetInstancesBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Instance>
+            {
+                new("Inst1") { Id = 1, AreaId = 1, SiteId = 1 }
+            });
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area> { new("Building A") { Id = 1, SiteId = 1 } });
+
+        var result = await _sut.DeleteAreaAsync(1, "admin");
+
+        Assert.True(result.IsFailure);
+        Assert.Contains("instance(s) are assigned", result.Error);
+    }
+
+    [Fact]
+    public async Task DeleteArea_WithChildAreas_ReturnsFailure()
+    {
+        _repoMock.Setup(r => r.GetAreaByIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Area("Parent") { Id = 1, SiteId = 1 });
+        _repoMock.Setup(r => r.GetInstancesBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Instance>());
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area>
+            {
+                new("Parent") { Id = 1, SiteId = 1 },
+                new("Child") { Id = 2, SiteId = 1, ParentAreaId = 1 }
+            });
+
+        var result = await _sut.DeleteAreaAsync(1, "admin");
+
+        Assert.True(result.IsFailure);
+        Assert.Contains("child areas", result.Error);
+    }
+
+    [Fact]
+    public async Task DeleteArea_NoConstraints_Success()
+    {
+        _repoMock.Setup(r => r.GetAreaByIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Area("Empty") { Id = 1, SiteId = 1 });
+        _repoMock.Setup(r => r.GetInstancesBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Instance>());
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area> { new("Empty") { Id = 1, SiteId = 1 } });
+        _repoMock.Setup(r => r.SaveChangesAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(1);
+
+        var result = await _sut.DeleteAreaAsync(1, "admin");
+
+        Assert.True(result.IsSuccess);
+        _repoMock.Verify(r => r.DeleteAreaAsync(1, It.IsAny<CancellationToken>()), Times.Once);
+    }
+
+    [Fact]
+    public async Task DeleteArea_InstancesInDescendants_Blocked()
+    {
+        // Area hierarchy: Area1 -> Area2 -> Area3
+        // Instance assigned to Area3, trying to delete Area1 should be blocked
+        _repoMock.Setup(r => r.GetAreaByIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Area("Root") { Id = 1, SiteId = 1 });
+        _repoMock.Setup(r => r.GetAreasBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Area>
+            {
+                new("Root") { Id = 1, SiteId = 1 },
+                new("Mid") { Id = 2, SiteId = 1, ParentAreaId = 1 },
+                new("Leaf") { Id = 3, SiteId = 1, ParentAreaId = 2 }
+            });
+        _repoMock.Setup(r => r.GetInstancesBySiteIdAsync(1, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Instance>
+            {
+                new("DeepInstance") { Id = 10, AreaId = 3, SiteId = 1 }
+            });
+
+        var result = await _sut.DeleteAreaAsync(1, "admin");
+
+        Assert.True(result.IsFailure);
+        Assert.Contains("instance(s) are assigned", result.Error);
+    }
+}