gnome-desktop-testing-runner: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/gnome-desktop-testing-runner - from package: gnome-desktop-testing

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