public void AddTrailingSeparatorTest()
{
String directory = null;
Assert.Throws <ArgumentNullException>(() => directory.AddTrailingSeparator());
directory = @"c:\temp";
Assert.AreEqual(directory + Path.DirectorySeparatorChar, directory.AddTrailingSeparator());
directory = @"c:\temp\";
Assert.AreEqual(directory, directory.AddTrailingSeparator());
}