If you are ensuring a system is producing correct outputs based on inputs, what type of testing would you apply?

If you are ensuring a system is producing correct outputs based on inputs, what type of testing would you apply?

For example, your business has a time sheet system. The only modifications you make to the system entails users must input their time on a daily basis, and that the system generated reports on a daily basis, rather than weekly?

Is it fair to say this would entail:

• System testing
• Acceptance testing
• (alternatively combined acceptance testing)

Thoughts?