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()); }