add resource example in the sample project

src/SIL.Harmony.Sample/Changes/AddWordImageChange.cs

@@ -0,0 +1,15 @@
+using SIL.Harmony.Changes;
+using SIL.Harmony.Entities;
+using SIL.Harmony.Sample.Models;
+
+namespace SIL.Harmony.Sample.Changes;
+
+public class AddWordImageChange(Guid entityId, Guid imageId) : EditChange<Word>(entityId), ISelfNamedType<AddWordImageChange>
+{
+    public Guid ImageId { get; } = imageId;
+
+    public override async ValueTask ApplyChange(Word entity, ChangeContext context)
+    {
+        if (!await context.IsObjectDeleted(ImageId)) entity.ImageResourceId = ImageId;
+    }
+}

src/SIL.Harmony.Sample/CrdtSampleKernel.cs

@@ -45,6 +45,7 @@ public static IServiceCollection AddCrdtDataSample(this IServiceCollection servi
                 .Add<SetWordTextChange>()
                 .Add<SetWordNoteChange>()
                 .Add<AddAntonymReferenceChange>()
+                .Add<AddWordImageChange>()
                 .Add<SetOrderChange<Definition>>()
                 .Add<SetDefinitionPartOfSpeechChange>()
                 .Add<DeleteChange<Word>>()

src/SIL.Harmony.Sample/Models/Word.cs

@@ -10,10 +10,17 @@ public class Word : IObjectBase<Word>
     public Guid Id { get; init; }
     public DateTimeOffset? DeletedAt { get; set; }
     public Guid? AntonymId { get; set; }
+    public Guid? ImageResourceId { get; set; }
 
     public Guid[] GetReferences()
     {
-        return AntonymId is null ? [] : [AntonymId.Value];
+        return Refs().ToArray();
+
+        IEnumerable<Guid> Refs()
+        {
+            if (AntonymId.HasValue) yield return AntonymId.Value;
+            if (ImageResourceId.HasValue) yield return ImageResourceId.Value;
+        }
     }
 
     public void RemoveReference(Guid id, Commit commit)

src/SIL.Harmony.Tests/ResourceTests/WordResourceTests.cs

@@ -0,0 +1,41 @@
+using System.Runtime.CompilerServices;
+using Microsoft.Extensions.DependencyInjection;
+using SIL.Harmony.Sample.Changes;
+using SIL.Harmony.Sample.Models;
+
+namespace SIL.Harmony.Tests.ResourceTests;
+
+public class WordResourceTests: DataModelTestBase
+{
+    private RemoteServiceMock _remoteServiceMock = new();
+    private ResourceService _resourceService => _services.GetRequiredService<ResourceService>();
+    private readonly Guid _entity1Id = Guid.NewGuid();
+
+    private string CreateFile(string contents, [CallerMemberName] string fileName = "")
+    {
+        var filePath = Path.GetFullPath(fileName + ".txt");
+        File.WriteAllText(filePath, contents);
+        return filePath;
+    }
+
+    [Fact]
+    public async Task CanReferenceAResourceFromAWord()
+    {
+        await WriteNextChange(SetWord(_entity1Id, "test-value"));
+        var imageFile = CreateFile("not image data");
+        //set commit date for add local resource
+        MockTimeProvider.SetNextDateTime(NextDate());
+        var resourceId = await _resourceService.AddLocalResource(imageFile, Guid.NewGuid(), resourceService: _remoteServiceMock);
+        await WriteNextChange(new AddWordImageChange(_entity1Id, resourceId));
+
+        var word = await DataModel.GetLatest<Word>(_entity1Id);
+        word.Should().NotBeNull();
+        word!.ImageResourceId.Should().Be(resourceId);
+
+
+        var localResource = await _resourceService.GetLocalResource(word.ImageResourceId!.Value);
+        localResource.Should().NotBeNull();
+        localResource!.LocalPath.Should().Be(imageFile);
+        (await File.ReadAllTextAsync(localResource.LocalPath)).Should().Be("not image data");
+    }
+}