Add tests to verify v9 behavior for sagas with custom finders (#812)

* Add custom finder test to v9

* Add tests to verify v9 behavior for sagas with custom finders

* Move version override

* AutomaticVersionRange="false"

* Order

* Remove unneeded package

---------

Co-authored-by: Brandon Ording <bording@gmail.com>

Author: andreasohlund

src/NServiceBus.Testing.Tests/Sagas/CustomFinder.cs

@@ -0,0 +1,106 @@
+namespace NServiceBus.Testing.Tests.Sagas;
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Extensibility;
+using NServiceBus.Sagas;
+using NUnit.Framework;
+using Persistence;
+
+[TestFixture]
+public class CustomFinder
+{
+    [Test]
+    public void TestSagaWithCustomFinderForMessageStartingTheSaga()
+    {
+        var exception = Assert.Throws<Exception>(() => new TestableSaga<SagaWithCustomFinderStarting, SagaWithCustomFinderStarting.SagaData>());
+
+        Assert.That(exception?.Message, Contains.Substring("Message type OrderBilled can start the saga SagaWithCustomFinderStarting (the saga implements IAmStartedByMessages<OrderBilled>) but does not map that message to saga data"));
+    }
+
+    [Test]
+    public async Task TestSagaWithCustomFinderForMessageNotStartingTheSaga()
+    {
+        var testableSaga = new TestableSaga<SagaWithCustomFinderNotStarting, SagaWithCustomFinderNotStarting.SagaData>();
+
+        var placeResult = await testableSaga.Handle(new OrderPlaced { OrderId = "abc" });
+
+        var exception = Assert.ThrowsAsync<Exception>(async () => await testableSaga.Handle(new OrderBilled { OrderId = "abc" }));
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(placeResult.Completed, Is.False);
+            Assert.That(placeResult.SagaDataSnapshot.Placed, Is.True);
+            Assert.That(placeResult.SagaDataSnapshot.Billed, Is.False);
+            Assert.That(exception?.Message, Contains.Substring("No mapped value found from message, could not look up saga data"));
+        });
+    }
+
+    public class SagaWithCustomFinderStarting : Saga<SagaWithCustomFinderStarting.SagaData>,
+        IAmStartedByMessages<OrderPlaced>,
+#pragma warning disable NSB0006
+        IAmStartedByMessages<OrderBilled>
+#pragma warning restore NSB0006
+    {
+        protected override void ConfigureHowToFindSaga(SagaPropertyMapper<SagaData> mapper) =>
+            mapper.MapSaga(saga => saga.OrderId)
+                .ToMessage<OrderPlaced>(msg => msg.OrderId);
+
+        public class MyFinder : ISagaFinder<SagaData, OrderBilled>
+        {
+            public Task<SagaData> FindBy(OrderBilled message, ISynchronizedStorageSession storageSession, IReadOnlyContextBag context, CancellationToken cancellationToken = new CancellationToken()) => throw new NotImplementedException();
+        }
+
+        public Task Handle(OrderPlaced message, IMessageHandlerContext context) => Task.FromResult(Data.Placed = true);
+
+        public Task Handle(OrderBilled message, IMessageHandlerContext context) => Task.FromResult(Data.Billed = true);
+
+        public class SagaData : ContainSagaData
+        {
+            public string OrderId { get; set; }
+            public bool Placed { get; set; }
+            public bool Billed { get; set; }
+        }
+    }
+
+    public class SagaWithCustomFinderNotStarting : Saga<SagaWithCustomFinderNotStarting.SagaData>,
+        IAmStartedByMessages<OrderPlaced>,
+        IHandleMessages<OrderBilled>
+    {
+        protected override void ConfigureHowToFindSaga(SagaPropertyMapper<SagaData> mapper) =>
+            mapper.MapSaga(saga => saga.OrderId)
+                .ToMessage<OrderPlaced>(msg => msg.OrderId);
+
+        public class MyFinder : ISagaFinder<SagaData, OrderBilled>
+        {
+            public Task<SagaData> FindBy(OrderBilled message, ISynchronizedStorageSession storageSession, IReadOnlyContextBag context, CancellationToken cancellationToken = new CancellationToken()) => throw new NotImplementedException();
+        }
+
+        public Task Handle(OrderPlaced message, IMessageHandlerContext context) => Task.FromResult(Data.Placed = true);
+
+        public Task Handle(OrderBilled message, IMessageHandlerContext context) => Task.FromResult(Data.Billed = true);
+
+        public class SagaData : ContainSagaData
+        {
+            public string OrderId { get; set; }
+            public bool Placed { get; set; }
+            public bool Billed { get; set; }
+        }
+    }
+
+    public class OrderPlaced : IEvent
+    {
+        public string OrderId { get; set; }
+    }
+
+    public class OrderBilled : IEvent
+    {
+        public string OrderId { get; set; }
+    }
+
+    public class OrderShipped : IEvent
+    {
+        public string OrderId { get; set; }
+    }
+}