public string GetPhysicalPath(string file) => Path.IsPathRooted(file) ? file : _impl.GetPhysicalPath(file);
public static IEnumerable <KeyValuePair <string, string> > GetAllPhysicalPaths(this IFileAbstractLayer fal) => from r in fal.GetAllInputFiles() select new KeyValuePair <string, string>(r, fal.GetPhysicalPath(r));