gnustep-tests: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/gnustep-tests - from package: gnustep-make

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/gnustep-tests - from package: gnustep-make

You may install the required package with command apt-get install {package}

Error in other languages:
gnustep-tests: bevel nie gevind nie
gnustep-tests: comandă negăsită
gnustep-tests: comando não encontrado
gnustep-tests: commande introuvable
gnustep-tests: command not found
gnustep-tests: käsku ei ole
gnustep-tests: không tìm thấy lệnh
gnustep-tests: komanda nerasta
gnustep-tests: Kommando nicht gefunden.
gnustep-tests: kommandot finns inte
gnustep-tests: komut yok
gnustep-tests: nie znaleziono polecenia
gnustep-tests: níor aimsíodh an t-ordú
gnustep-tests: no se encontró la orden
gnustep-tests: no s'ha trobat l'ordre
gnustep-tests: opdracht niet gevonden
gnustep-tests: parancs nem található
gnustep-tests: perintah tidak ditemukan
gnustep-tests: príkaz nenájdený
gnustep-tests: příkaz nenalezen
gnustep-tests: команда не найдена
gnustep-tests: командата не е открита
gnustep-tests: 命令找不到
gnustep-tests: コマンドが見つかりません