Question

I’ve started using TransactionScope to help with my unit tests, in order to put my test database back to it’s previous state. Using this with SpecFlow, I have a base class like so:

public class TransactionScopedFeature
{
    private TransactionScope Scope { get; set; }

    [BeforeScenario]
    public void BaseSetup()
    {
        this.Scope = new TransactionScope(TransactionScopeOption.RequiresNew);
    }

    [AfterScenario]
    public void BaseCleanup()
    {
        if (this.Scope != null)
        {
            this.Scope.Dispose();
        }
    }
}

All of the above works, in that when I add records to the database, when I then query the tables after the tests have finished, those tables are empty. Great stuff, and very clever indeed!

My question relates to identity columns in these tables. What I’ve noticed is that, when I run my tests numerous times, the ID column of my test table increases by 1. I assumed that since the TransactionScope would rollback the changes, that the identity seed would also be rolled back.

Am I wrong in making this assumption – is this just how databases work? If that is the case, I could also run a SQL script before each of my scenarios that does this:

DBCC CHECKIDENT ('dbo.Items', reseed, 0)

I just wanted to check in case I was doing something wrong, or this is normal database behaviour.

Cheers.
Jas.

Answer 1

The seed value for an identity column does not get rolled back with the rest of a transaction in SQL Server.

This is by design so that an exclusive lock does not have to be placed on the counter for the identity for the entire duration of the transaction.