WrongExpectedVersionException on EventStore Getting started project - eventstoredb

Question

I have re-written the getting-started-with-event-store project to learn what's going on and now for the test CanSaveExistingAggregate() I am getting a WrongExpectedVersionException. The thing is, in order to try and work out what's going on I would like to know what the expected version should be, how can I find this out? In the test, the line repository.Save(firstSaved, Guid.NewGuid(), d => { }); calculates the expected version as 101 and this is where it fails:
[Test]
public void CanSaveExistingAggregate()
{
var savedId = SaveTestAggregateWithoutCustomHeaders(repository, 100 /* excludes TestAggregateCreated */);
var firstSaved = repository.GetById<TestAggregate>(savedId);
Console.WriteLine("version:" + firstSaved.Id);
firstSaved.ProduceEvents(50);
repository.Save(firstSaved, Guid.NewGuid(), d => { });
var secondSaved = repository.GetById<TestAggregate>(savedId);
Assert.AreEqual(150, secondSaved.AppliedEventCount);
}
And the code where the exception is thrown:
public void Save(CommonDomain.IAggregate aggregate, Guid commitId, Action<IDictionary<string, object>> updateHeaders)
{
var commitHeaders = new Dictionary<string, object>
{
{CommitIdHeader, commitId},
{AggregateClrTypeHeader, aggregate.GetType().AssemblyQualifiedName}
};
updateHeaders(commitHeaders);
var streamName = aggregateIdToStreamName(aggregate.GetType(), aggregate.Id);
var newEvents = aggregate.GetUncommittedEvents().Cast<object>().ToList();
var originalVersion = aggregate.Version - newEvents.Count;
var expectedVersion = originalVersion == 0 ? ExpectedVersion.NoStream : originalVersion;
var eventsToSave = newEvents.Select(e => ToEventData(Guid.NewGuid(), e, commitHeaders)).ToList();
if (eventsToSave.Count < WritePageSize)
{
eventStoreConnection.AppendToStream(streamName, expectedVersion, eventsToSave);
}
else
{
var transaction = eventStoreConnection.StartTransaction(streamName, expectedVersion);
var position = 0;
while (position < eventsToSave.Count)
{
var pageEvents = eventsToSave.Skip(position).Take(WritePageSize);
transaction.Write(pageEvents);
position += WritePageSize;
}
transaction.Commit();
}
aggregate.ClearUncommittedEvents();
}
All the other tests pass (except ThrowsOnGetDeletedAggregate() but I'll ask about that later) but I think this is the only test that has expectedVersion != ThrowsOnGetDeletedAggregate()

Answer 1

Well it turns out it was just a mistake when writing the code, rather than
var expectedVersion = originalVersion == 0 ? ExpectedVersion.NoStream : originalVersion;
it should be
var expectedVersion = originalVersion == 0 ? ExpectedVersion.NoStream : originalVersion - 1;