Event-Sourcing support

NetChris.Core.UnitTests/Paging/MapToTests.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using FluentAssertions;
+using NetChris.Core.Paging;
+using Xunit;
+
+namespace NetChris.Core.UnitTests.Paging;
+
+public class MapToTests
+{
+    private class FromType
+    {
+        public string Name { get; set; } = null!;
+        public int Age { get; set; }
+    }
+
+    private class ToType
+    {
+        public string PersonName { get; set; } = null!;
+        public TimeSpan Age { get; set; }
+    }
+
+
+    private readonly List<FromType> _fromTypes = new()
+    {
+        new FromType { Name = "Alice", Age = 30 },
+        new FromType { Name = "Bob", Age = 25 },
+        new FromType { Name = "Charlie", Age = 35 },
+        new FromType { Name = "Diana", Age = 28 }
+    };
+
+
+    private readonly Page<FromType> _sourcePage;
+    private readonly Page<ToType> _targetPage;
+
+    private static ToType MappingFunction(FromType from)
+    {
+        return new ToType
+        {
+            PersonName = from.Name,
+            Age = TimeSpan.FromDays(from.Age * 365.25),
+        };
+    }
+
+    public MapToTests()
+    {
+        _sourcePage = new Page<FromType>(_fromTypes, 2, 4, 500);
+        _targetPage = _sourcePage.MapTo(MappingFunction);
+    }
+
+    [Fact]
+    public void TotalPagesShouldBeCorrect()
+    {
+        _targetPage.TotalPages.Should().Be(_sourcePage.TotalPages);
+    }
+
+    [Fact]
+    public void CurrentPageShouldBeCorrect()
+    {
+        _targetPage.CurrentPage.Should().Be(_sourcePage.CurrentPage);
+    }
+
+    [Fact]
+    public void PageSizeShouldBeCorrect()
+    {
+        _targetPage.PageSize.Should().Be(_sourcePage.PageSize);
+    }
+
+    [Fact]
+    public void MappedItemShouldMatch()
+    {
+        var charlieFromSourcePage = _sourcePage.Items.ElementAt(2);
+        var charlieFromTargetPage = _targetPage.Items.ElementAt(2);
+
+        charlieFromTargetPage.PersonName.Should().Be(charlieFromSourcePage.Name);
+        charlieFromTargetPage.Age.Should().Be(
+            TimeSpan.FromDays(charlieFromSourcePage.Age * 365.25));
+    }
+}

NetChris.Core/Paging/Extensions.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Linq;
+
+namespace NetChris.Core.Paging;
+
+/// <summary>
+/// Extension methods for paging
+/// </summary>
+public static class Extensions
+{
+    /// <summary>
+    /// Get a page of items of type <typeparamref name="TTo"/>
+    /// mapped from a page of items of type <typeparamref name="T"/>
+    /// </summary>
+    /// <param name="sourcePage">The source page</param>
+    /// <param name="mappingFunction">The mapping function from <typeparamref name="T"/> to <typeparamref name="TTo"/></param>
+    public static Page<TTo> MapTo<T, TTo>(this Page<T> sourcePage, Func<T, TTo> mappingFunction)
+    {
+        var resultItems = sourcePage.Items.Select(mappingFunction).ToList();
+
+        return new Page<TTo>(
+            resultItems,
+            sourcePage.CurrentPage,
+            sourcePage.PageSize,
+            sourcePage.TotalItems);
+    }
+}