Testing improvement

[ChacaS0]

Write unit tests

For cmd package:

• add.go
• get.go
• init.go
• list.go
• rm.go
• set.go
• start.go
• purge.go
• update.go
• version.go
• doc.go
• root.go

This might even get followed by a new command like tempest debug or something to see what's wrong. In that case a new issue or task will be created.