Allow recreating deleted entities instead of throwing

backend/FwLite/LcmCrdt.Tests/Changes/UseChangesTests.cs

@@ -72,15 +72,19 @@ public async Task CanSyncAllChangesWithDuplicates()
                 change.GetType()) as IChange;
             duplicateChange.Should().NotBeNull();
             duplicateChange.GetType().Should().Be(change.GetType());
-            // we can't create duplicate entities with the same ID
-            if (IsCreateChange(change)) duplicateChange.EntityId = Guid.NewGuid();
-            else if (duplicateChange is AddTranslationChange addTranslationChange)
+            await fixture.DataModel.AddChange(Guid.NewGuid(), duplicateChange);
+
+            if (change.SupportsNewEntity())
             {
-                // translations aren't "primary entities" created with a CreateChange<>
-                // but they are still (correctly) enforced to have unique IDs (at least within a single ExampleSentence)
-                addTranslationChange.Translation.Id = Guid.NewGuid();
+                // The previous duplicate change is presumably a no-op, so we'll make a duplicate entity with a different ID as well.
+                var duplicateCreateChange = JsonSerializer.Deserialize(
+                    JsonSerializer.Serialize(change, Options),
+                    change.GetType()) as IChange;
+                duplicateCreateChange.Should().NotBeNull();
+                duplicateCreateChange.EntityId = Guid.NewGuid();
+                duplicateCreateChange.GetType().Should().Be(change.GetType());
+                await fixture.DataModel.AddChange(Guid.NewGuid(), duplicateCreateChange);
             }
-            await fixture.DataModel.AddChange(Guid.NewGuid(), duplicateChange);
 
             var allEntries = await fixture.Api.GetEntries().ToArrayAsync();
             var result = await EntrySync.SyncFull(allEntries, allEntries, fixture.Api);
@@ -256,18 +260,4 @@ private static IEnumerable<ChangeWithDependencies> GetAllChanges()
             new RemoteResourceUploadedChange(createRemoteResourcePendingUploadChange.EntityId, "test-remote-id"),
             [createRemoteResourcePendingUploadChange]);
     }
-
-    private static bool IsCreateChange(IChange obj)
-    {
-        var type = obj.GetType();
-        while (type != null && type != typeof(object))
-        {
-            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(CreateChange<>))
-            {
-                return true;
-            }
-            type = type.BaseType;
-        }
-        return false;
-    }
 }

backend/FwLite/LcmCrdt/Changes/ExampleSentences/AddTranslationChange.cs

@@ -1,4 +1,3 @@
-using System.Diagnostics;
 using SIL.Extensions;
 using SIL.Harmony.Changes;
 using SIL.Harmony.Core;
@@ -12,10 +11,8 @@ public class AddTranslationChange(Guid entityId, Translation translation) : Edit
 
     public override ValueTask ApplyChange(ExampleSentence entity, IChangeContext context)
     {
-        var existingTranslation = entity.Translations.FirstOrDefault(t => t.Id == Translation.Id);
-        Debug.Assert(existingTranslation == null, $"Translation with ID {Translation.Id} already exists in the ExampleSentence with ID ({entity.Id})");
-        if (existingTranslation != null) entity.Translations.RemoveAll(t => t.Id == Translation.Id);
-
+        // could happen if Chorus recreates a translation due to a merge conflict.
+        entity.Translations.RemoveAll(t => t.Id == Translation.Id);
         entity.Translations.Add(Translation);
         return ValueTask.CompletedTask;
     }

backend/FwLite/LcmCrdt/CrdtMiniLcmApi.cs

@@ -311,7 +311,8 @@ public async Task<ComplexFormComponent> CreateComplexFormComponent(ComplexFormCo
         var existing = await repo.FindComplexFormComponent(complexFormComponent);
         if (existing is null)
         {
-            var betweenIds = between is null ? null : new BetweenPosition(between.Previous?.Id, between.Next?.Id);
+            // todo test between items missing IDs (i.e. from LibLCM)
+            var betweenIds = between is null ? null : await between.MapAsync(async c => (await repo.FindComplexFormComponent(c))?.Id);
             var addEntryComponentChange = await repo.CreateComplexFormComponentChange(complexFormComponent, betweenIds);
             await AddChange(addEntryComponentChange);
             return await repo.FindComplexFormComponent(addEntryComponentChange.EntityId);
@@ -336,7 +337,11 @@ public async Task MoveComplexFormComponent(ComplexFormComponent component, Betwe
 
     public async Task DeleteComplexFormComponent(ComplexFormComponent complexFormComponent)
     {
-        await AddChange(new DeleteChange<ComplexFormComponent>(complexFormComponent.Id));
+        // todo test missing ID (i.e. from LibLCM)
+        await using var repo = await repoFactory.CreateRepoAsync();
+        var existing = await repo.FindComplexFormComponent(complexFormComponent);
+        if (existing is null) return;
+        await AddChange(new DeleteChange<ComplexFormComponent>(existing.Id));
     }
 
     public async Task AddComplexFormType(Guid entryId, Guid complexFormTypeId)

backend/FwLite/MiniLcm.Tests/ExampleSentenceTestsBase.cs

@@ -154,4 +154,23 @@ public async Task RemoveTranslation_RemovesExistingTranslation()
         reloaded.Should().NotBeNull();
         reloaded.Translations.Should().BeEmpty();
     }
+
+    /// <summary>
+    /// Tests that a deleted example-sentence can be recreated.
+    /// This is necessary if Chorus recreates an example-sentence due to a merge conflict.
+    /// </summary>
+    [Fact]
+    public async Task RecreateDeletedExampleSentence()
+    {
+        var initial = await Api.GetExampleSentence(_entryId, _senseId, _exampleSentenceId);
+        initial.Should().NotBeNull();
+
+        await Api.DeleteExampleSentence(_entryId, _senseId, _exampleSentenceId);
+        var deleted = await Api.GetExampleSentence(_entryId, _senseId, _exampleSentenceId);
+        deleted.Should().BeNull();
+
+        var recreated = await Api.CreateExampleSentence(_entryId, _senseId, initial);
+        recreated.Should().NotBeNull();
+        recreated.Should().BeEquivalentTo(initial);
+    }
 }

backend/FwLite/MiniLcm.Tests/SenseTestsBase.cs

@@ -34,4 +34,23 @@ public async Task Get_ExistingSense_ReturnsSense()
         sense.Should().NotBeNull();
         sense.Gloss["en"].Should().Be("new-sense-gloss");
     }
+
+    /// <summary>
+    /// Tests that a deleted sense can be recreated.
+    /// This is necessary if Chorus recreates a sense due to a merge conflict.
+    /// </summary>
+    [Fact]
+    public async Task RecreateDeletedSense()
+    {
+        var initial = await Api.GetSense(_entryId, _senseId);
+        initial.Should().NotBeNull();
+
+        await Api.DeleteSense(_entryId, _senseId);
+        var deleted = await Api.GetSense(_entryId, _senseId);
+        deleted.Should().BeNull();
+
+        var recreated = await Api.CreateSense(_entryId, initial);
+        recreated.Should().NotBeNull();
+        recreated.Should().BeEquivalentTo(initial);
+    }
 }

backend/FwLite/MiniLcm.Tests/UpdateEntryTestsBase.cs

@@ -333,4 +333,23 @@ public async Task UpdateEntry_CanReorderComponents(string before, string after,
             actualOrderValues.Should().Be(expectedOrderValues);
         }
     }
+
+    /// <summary>
+    /// Tests that a deleted entry can be recreated.
+    /// This is necessary if Chorus recreates an entry due to a merge conflict.
+    /// </summary>
+    [Fact]
+    public async Task RecreateDeletedEntry()
+    {
+        var initial = await Api.GetEntry(Entry1Id);
+        initial.Should().NotBeNull();
+
+        await Api.DeleteEntry(Entry1Id);
+        var deleted = await Api.GetEntry(Entry1Id);
+        deleted.Should().BeNull();
+
+        var recreated = await Api.CreateEntry(initial);
+        recreated.Should().NotBeNull();
+        recreated.Should().BeEquivalentTo(initial);
+    }
 }