using(SvnClient client = new SvnClient())
{
    SvnStatusArgs sa = new SvnStatusArgs();
    sa.Depth = SvnDepth.Empty; // Adjust this to check direct files,or (recursive) directories etc

    Collection<SvnStatusEventArgs> statuses;
    client.GetStatus("c:\\somefile.txt",sa,out statuses); 

    Assert.That(statuses.Count,Is.EqualTo(1));
    Assert.That(SvnStatus.NotVersioned,Is.EqualTo(statuses[0].LocalContentStatus));
}