ConcurrencyTestAsync(Action<F1Context>, Action<F1Context>, Action<F1Context, DbUpdateException>, Action<F1Context>)
ConcurrencyTestAsync(Action(Of F1Context), Action(Of F1Context), Action(Of F1Context, DbUpdateException), Action(Of F1Context))
Runs the two actions with two different contexts and calling
SaveChanges such that storeChange will succeed and the store will reflect this change, and
then clientChange will result in a concurrency exception.
After the exception is caught the resolver action is called, after which SaveChanges is called
again. Finally, a new context is created and the validator is called so that the state of
the database at the end of the process can be validated.