test: add unit tests for push notification infrastructure

Tests cover DeviceTokenService (register/upsert/unregister),
PushNotificationService (no-op when Firebase unconfigured), and
integration verification that push triggers fire after absence/handover
create/approve/reject.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: renemadsen

eFormAPI/Plugins/TimePlanning.Pn/TimePlanning.Pn.Test/DeviceTokenServiceTests.cs

@@ -0,0 +1,109 @@
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using NSubstitute;
+using NUnit.Framework;
+using TimePlanning.Pn.Infrastructure.Models.DeviceToken;
+using TimePlanning.Pn.Services.DeviceTokenService;
+
+namespace TimePlanning.Pn.Test;
+
+[TestFixture]
+public class DeviceTokenServiceTests
+{
+    private DeviceTokenDbContext _dbContext = null!;
+    private DeviceTokenService _service = null!;
+
+    [SetUp]
+    public void SetUp()
+    {
+        var options = new DbContextOptionsBuilder<DeviceTokenDbContext>()
+            .UseInMemoryDatabase(databaseName: $"DeviceTokenTestDb_{TestContext.CurrentContext.Test.Name}")
+            .Options;
+        _dbContext = new DeviceTokenDbContext(options);
+        _service = new DeviceTokenService(
+            _dbContext,
+            Substitute.For<ILogger<DeviceTokenService>>());
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        _dbContext.Database.EnsureDeleted();
+        _dbContext.Dispose();
+    }
+
+    [Test]
+    public async Task RegisterAsync_NewToken_IsStored()
+    {
+        // Act
+        var result = await _service.RegisterAsync(42, "fcm-token-abc", "android");
+
+        // Assert
+        Assert.That(result.Success, Is.True);
+
+        var stored = await _dbContext.DeviceTokens.SingleAsync();
+        Assert.That(stored.SdkSiteId, Is.EqualTo(42));
+        Assert.That(stored.Token, Is.EqualTo("fcm-token-abc"));
+        Assert.That(stored.Platform, Is.EqualTo("android"));
+        Assert.That(stored.WorkflowState, Is.EqualTo("created"));
+    }
+
+    [Test]
+    public async Task RegisterAsync_SameTokenTwice_UpsertsWithoutDuplicate()
+    {
+        // Arrange
+        await _service.RegisterAsync(1, "dup-token", "android");
+
+        // Act — re-register same token with different site
+        var result = await _service.RegisterAsync(2, "dup-token", "ios");
+
+        // Assert
+        Assert.That(result.Success, Is.True);
+        Assert.That(await _dbContext.DeviceTokens.CountAsync(), Is.EqualTo(1));
+
+        var stored = await _dbContext.DeviceTokens.SingleAsync();
+        Assert.That(stored.SdkSiteId, Is.EqualTo(2));
+        Assert.That(stored.Platform, Is.EqualTo("ios"));
+    }
+
+    [Test]
+    public async Task UnregisterAsync_ExistingToken_IsRemoved()
+    {
+        // Arrange
+        await _service.RegisterAsync(1, "remove-me", "android");
+        Assert.That(await _dbContext.DeviceTokens.CountAsync(), Is.EqualTo(1));
+
+        // Act
+        var result = await _service.UnregisterAsync("remove-me");
+
+        // Assert
+        Assert.That(result.Success, Is.True);
+        Assert.That(await _dbContext.DeviceTokens.CountAsync(), Is.EqualTo(0));
+    }
+
+    [Test]
+    public async Task UnregisterAsync_NonExistentToken_SucceedsWithoutError()
+    {
+        // Act
+        var result = await _service.UnregisterAsync("does-not-exist");
+
+        // Assert
+        Assert.That(result.Success, Is.True);
+    }
+
+    [Test]
+    public async Task RegisterAsync_EmptyToken_FailsGracefully()
+    {
+        // The DB has a [Required] Token column. With InMemory provider the constraint
+        // isn't enforced at the DB level, but we still verify the service doesn't crash
+        // and that an empty-string token is handled.
+        var result = await _service.RegisterAsync(1, "", "android");
+
+        // The service doesn't explicitly validate empty tokens — it succeeds but stores
+        // an empty string. This test documents the current behaviour; a future guard
+        // could make this return Success=false.
+        Assert.That(result.Success, Is.True);
+    }
+}