PomodoroTimeTracker.Tests/
├── ViewModels/                    (158 tests)
│   ├── PomodoroViewModelTests.cs     (60)
│   ├── RegularTimerViewModelTests.cs (40)
│   ├── StopWatchViewModelTests.cs    (30)
│   └── ...
├── Application/Services/          (148 tests)
│   ├── PomodoroSessionServiceTests.cs
│   ├── AudioServiceTests.cs          (35)
│   └── ...
└── Infrastructure/Repositories/   (71 tests)

public class ViewModelTests
{
    private readonly Mock<IService> _service;
    private readonly Mock<IDispatcherTimer> _timer;
    private readonly ViewModel _viewModel;

    public ViewModelTests()
    {
        _service = new Mock<IService>();
        _timer = new Mock<IDispatcherTimer>();
        _viewModel = new ViewModel(_service.Object, _timer.Object);
    }

    [Fact]
    public void Property_WhenChanged_UpdatesDependentProperties()
    {
        // Arrange
        var propertyChanges = new List<string>();
        _viewModel.PropertyChanged += (s, e) => propertyChanges.Add(e.PropertyName!);

        // Act
        _viewModel.SomeProperty = "value";

        // Assert
        propertyChanges.Should().Contain("DependentProperty");
    }
}

public class ServiceTests : IDisposable
{
    private readonly ApplicationDbContext _context;
    private readonly Service _service;

    public ServiceTests()
    {
        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;
        _context = new ApplicationDbContext(options);
        _service = new Service(new UnitOfWork(_context));
    }

    public void Dispose()
    {
        _context.Database.EnsureDeleted();
        _context.Dispose();
    }
}