price adjustment and stock adjustments

Backend/ERPCore.Tests/LowStockAlertServiceTests.cs

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+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Dtos.Common;
+using ERPCore.Dtos.Notifications;
+using ERPCore.Dtos.Stock;
+using ERPCore.Infra.Persistence;
+using ERPCore.Repositories;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using ERPCore.Tests.TestSupport;
+
+namespace ERPCore.Tests;
+
+/// <summary>Low-stock / reorder alerts raised after stock issues.</summary>
+public class LowStockAlertServiceTests
+{
+    private const int ItemId = 1, WarehouseId = 1;
+
+    [Theory]
+    [InlineData(12, 4, 8, true)]    // 12 → 8 crosses the alert level of 10
+    [InlineData(12, 2, 10, true)]   // landing exactly on the level counts
+    [InlineData(20, 5, 15, false)]  // still above the level
+    [InlineData(9, 3, 6, false)]    // was already low — no repeat alert on every sale
+    public async Task Alerts_OnlyWhenAnIssueCrossesTheReorderPoint(decimal before, decimal issued, decimal after, bool alerts)
+    {
+        Assert.Equal(before - issued, after);
+        await using var db = Seed();
+        var tracker = new LowStockTracker();
+        tracker.Track(ItemId, WarehouseId, issued);
+        var notifications = new RecordingNotifications();
+
+        await Service(db, tracker, after, notifications).CheckAsync();
+
+        if (!alerts)
+        {
+            Assert.Empty(notifications.Raised);
+            return;
+        }
+        var raised = Assert.Single(notifications.Raised);
+        Assert.Equal(LowStockAlertService.ModuleKey, raised.ModuleKey);
+        Assert.Contains("SKU-1", raised.Message);
+        Assert.Contains($"down to {after:0.####} pcs at WH-1", raised.Message);
+        Assert.Contains("Suggested reorder: 50 pcs", raised.Message);
+    }
+
+    [Fact]
+    public async Task ItemsWithoutARule_OrUntouched_AreIgnored()
+    {
+        await using var db = Seed();
+        var tracker = new LowStockTracker();
+        tracker.Track(itemId: 99, WarehouseId, 100);     // no rule for this item
+        var notifications = new RecordingNotifications();
+
+        await Service(db, tracker, available: 0, notifications).CheckAsync();
+        await Service(db, new LowStockTracker(), available: 0, notifications).CheckAsync();  // nothing issued
+
+        Assert.Empty(notifications.Raised);
+    }
+
+    [Fact]
+    public async Task Tracker_SumsIssuesWithinARequest_AndEmptiesWhenDrained()
+    {
+        var tracker = new LowStockTracker();
+        tracker.Track(ItemId, WarehouseId, 3);
+        tracker.Track(ItemId, WarehouseId, 4);
+        tracker.Track(ItemId, WarehouseId, 0);
+
+        Assert.Equal(7m, tracker.Drain()[(ItemId, WarehouseId)]);
+        Assert.Empty(tracker.Drain());
+    }
+
+    private static LowStockAlertService Service(ErpDbContext db, LowStockTracker tracker, decimal available, INotificationService notifications)
+        => new(tracker, new Repository<ItemReorder>(db), new FixedStock(available), notifications);
+
+    private static ErpDbContext Seed()
+    {
+        var db = BankDepositTestSupport.CreateContext();   // users, branches, warehouses WH-1 / WH-2
+        db.Uoms.Add(new Uom { UomId = 1, Name = "pcs" });
+        db.Items.Add(new Item { ItemId = ItemId, Sku = "SKU-1", Name = "Cola 500ml", BaseUomId = 1, CategoryId = 1 });
+        db.ItemReorders.Add(new ItemReorder { ReorderId = 1, ItemId = ItemId, WarehouseId = WarehouseId, ReorderPoint = 10, ReorderQty = 50 });
+        db.SaveChanges();
+        return db;
+    }
+
+    private sealed class FixedStock(decimal available) : IStockService
+    {
+        public Task<StockOnHandDto> GetOnHandAsync(int itemId, int warehouseId, CancellationToken ct = default)
+            => Task.FromResult(new StockOnHandDto(itemId, warehouseId, available, available, 0, 0, 0, DateTime.UtcNow));
+        public Task<PagedResponse<StockOnHandDto>> GetOnHandListAsync(int? itemId, int? warehouseId, int? branchId, PageQuery query, CancellationToken ct = default)
+            => throw new NotSupportedException();
+        public Task<IReadOnlyDictionary<int, decimal>> GetAvailableByItemAsync(int warehouseId, CancellationToken ct = default)
+            => throw new NotSupportedException();
+        public Task<PagedResponse<StockLedgerRowDto>> GetLedgerAsync(int? itemId, int? warehouseId, int? branchId, DateOnly? from, DateOnly? to,
+            string? sourceDocType, int? sourceDocId, PageQuery query, CancellationToken ct = default) => throw new NotSupportedException();
+        public Task<StockValuationDto> GetValuationAsync(int itemId, int warehouseId, CancellationToken ct = default)
+            => throw new NotSupportedException();
+    }
+
+    private sealed class RecordingNotifications : INotificationService
+    {
+        public List<(string ModuleKey, string Title, string Message)> Raised { get; } = new();
+
+        public Task RaiseAsync(string moduleKey, string title, string message, string? relatedEntityType = null,
+            int? relatedEntityId = null, CancellationToken ct = default)
+        {
+            Raised.Add((moduleKey, title, message));
+            return Task.CompletedTask;
+        }
+
+        public Task NotifyUsersAsync(IEnumerable<int> userIds, string moduleKey, string title, string message,
+            string? relatedEntityType = null, int? relatedEntityId = null, CancellationToken ct = default) => throw new NotSupportedException();
+
+        public Task<NotificationFeedDto> GetFeedAsync(int userId, int take = 20, CancellationToken ct = default) => throw new NotSupportedException();
+        public Task MarkAllReadAsync(int userId, CancellationToken ct = default) => throw new NotSupportedException();
+    }
+}