added unit tests
added unit tests

to confirm bug https://github.com/NLog/NLog/issues/957

AndreGleichner/NLog,littlesmilelove/NLog,BrutalCode/NLog,bjornbouetsmith/NLog,304NotModified/NLog,hubo0831/NLog,bryjamus/NLog,MartinTherriault/NLog,luigiberrettini/NLog,hubo0831/NLog,ArsenShnurkov/NLog,littlesmilelove/NLog,sean-gilliam/NLog,FeodorFitsner/NLog,breyed/NLog,AndreGleichner/NLog,UgurAldanmaz/NLog,snakefoot/NLog,tohosnet/NLog,pwelter34/NLog,FeodorFitsner/NLog,bjornbouetsmith/NLog,BrutalCode/NLog,ArsenShnurkov/NLog,nazim9214/NLog,bhaeussermann/NLog,MoaidHathot/NLog,bhaeussermann/NLog,NLog/NLog,Niklas-Peter/NLog,UgurAldanmaz/NLog,ilya-g/NLog,michaeljbaird/NLog,ie-zero/NLog,MoaidHathot/NLog,MartinTherriault/NLog,luigiberrettini/NLog,kevindaub/NLog,michaeljbaird/NLog,ie-zero/NLog,ilya-g/NLog,Niklas-Peter/NLog,tetrodoxin/NLog,pwelter34/NLog,nazim9214/NLog,tetrodoxin/NLog,bryjamus/NLog,tohosnet/NLog,kevindaub/NLog,breyed/NLog