Update README.md with project details, features, requirements, architecture, and data management for PLib video library manager.

tests/PLib.Tests/Library/InMemoryVideoRepository.cs

@@ -0,0 +1,50 @@
+using PLib.Application.Abstractions;
+using PLib.Application.Library;
+using PLib.Domain.Videos;
+
+namespace PLib.Tests.Library;
+
+/// <summary>
+/// A hand-written double rather than a mock: the scan logic is all about what ends up in the
+/// repository, so the tests read better when they can just look at the resulting list.
+/// </summary>
+internal sealed class InMemoryVideoRepository : IVideoRepository
+{
+    private readonly Dictionary<string, VideoItem> _items = new(LibraryPathComparer.Instance);
+
+    public int SaveCount { get; private set; }
+
+    public IReadOnlyCollection<VideoItem> Items => _items.Values;
+
+    public void Seed(params VideoItem[] items)
+    {
+        foreach (var item in items)
+        {
+            _items[item.FullPath] = item;
+        }
+    }
+
+    public Task<IReadOnlyList<VideoItem>> GetAllAsync(CancellationToken cancellationToken = default) =>
+        Task.FromResult<IReadOnlyList<VideoItem>>([.. _items.Values]);
+
+    public Task<VideoItem?> FindByPathAsync(string fullPath, CancellationToken cancellationToken = default) =>
+        Task.FromResult(_items.GetValueOrDefault(fullPath));
+
+    public Task AddAsync(VideoItem item, CancellationToken cancellationToken = default)
+    {
+        _items[item.FullPath] = item;
+        return Task.CompletedTask;
+    }
+
+    public Task RemoveAsync(VideoItem item, CancellationToken cancellationToken = default)
+    {
+        _items.Remove(item.FullPath);
+        return Task.CompletedTask;
+    }
+
+    public Task SaveChangesAsync(CancellationToken cancellationToken = default)
+    {
+        SaveCount++;
+        return Task.CompletedTask;
+    }
+}