Created a failing test for a bug with inline lifecycle and using fetc…

…hForWriting

src/EventSourcingTests/Bugs/Bug_fetch_for_writing_cache.cs

@@ -0,0 +1,64 @@
+using Marten.Events;
+using Marten.Events.Aggregation;
+using Marten.Events.Projections;
+using Marten.Schema;
+using Marten.Testing.Harness;
+using System;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace EventSourcingTests.Bugs;
+
+public class Bug_fetch_for_writing_cache: BugIntegrationContext
+{
+    [Fact]
+    public async Task Test()
+    {
+        StoreOptions(opts =>
+        {
+            opts.Events.StreamIdentity = StreamIdentity.AsString;
+            opts.Projections.Add<TestProjection2>(ProjectionLifecycle.Inline);
+            opts.Schema
+                .For<TestAggregate>()
+                .Identity(x => x.StreamKey);
+        });
+
+        var streamKey = Guid.NewGuid().ToString();
+
+        theSession.Events.StartStream(streamKey, new NamedEvent2("foo"));
+        await theSession.SaveChangesAsync();
+
+        var test = await theSession.Events.FetchForWriting<TestAggregate>(streamKey);
+        test.AppendOne(new NamedEvent2("bar"));
+        //await theSession.Events.AppendOptimistic(streamKey, new NamedEvent2("bar")); If I commented the two lines above and uncommented this one it works fine
+        await theSession.SaveChangesAsync();
+
+        test = await theSession.Events.FetchForWriting<TestAggregate>(streamKey);
+        Assert.Equal("bar", test.Aggregate.Name);
+    }
+
+}
+
+public record NamedEvent2(string Name);
+
+public class TestProjection2: SingleStreamProjection<TestAggregate>
+{
+    public TestAggregate Create(NamedEvent2 @event)
+    => new TestAggregate(@event.Name);
+
+    public TestAggregate Apply(NamedEvent2 @event, TestAggregate aggregate)
+    => aggregate with { Name = @event.Name };
+}
+
+public record TestAggregate
+{
+    public TestAggregate(string name)
+    {
+        Name = name;
+    }
+
+    [Identity]
+    public string StreamKey { get; set; } = null!;
+
+    public string Name { get; set; } = null!;
+}