convert_to_should_syntax: 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/convert_to_should_syntax - from package: rubygem-shoulda
/usr/lib/ruby/gems/1.8/gems/shoulda-2.11.3/bin/convert_to_should_syntax - from package: rubygem-shoulda

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

On Debian possible default full paths are:

/usr/bin/convert_to_should_syntax - from package: ruby-shoulda-context

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

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