shunit2: 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 Debian possible default full paths are:

/usr/bin/shunit2 - from package: shunit2

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

Error in other languages:
shunit2: bevel nie gevind nie
shunit2: comandă negăsită
shunit2: comando não encontrado
shunit2: commande introuvable
shunit2: command not found
shunit2: käsku ei ole
shunit2: không tìm thấy lệnh
shunit2: komanda nerasta
shunit2: Kommando nicht gefunden.
shunit2: kommandot finns inte
shunit2: komut yok
shunit2: nie znaleziono polecenia
shunit2: níor aimsíodh an t-ordú
shunit2: no se encontró la orden
shunit2: no s'ha trobat l'ordre
shunit2: opdracht niet gevonden
shunit2: parancs nem található
shunit2: perintah tidak ditemukan
shunit2: príkaz nenájdený
shunit2: příkaz nenalezen
shunit2: команда не найдена
shunit2: командата не е открита
shunit2: 命令找不到
shunit2: コマンドが見つかりません