The Path.GetDirectoryName call in Compiler.CompileFromDotNetText is unnecessary since AppDomain.CurrentDomain.BaseDirectory is always a directory.
Later path concatenation is already done by Path.Combine() which handles any trailing slash.
Removing Path.GetDirectoryName() will not affect the runtime but allows NUnit to work since it doesn't add a trailing slash to AppDomain.CurrentDomain.BaseDirectory.
"First stage in a major Script Engine refactor, that will result in the LSL implementaions ebing reconverged. Not there yet, but one major part is done."
Thank you, Melanie!