Can you please give me some ideas on what kind of questions can be asked while I perform the internal audit to the HR team, Testing team
Generally you need to verify if the HR team is compliant with the domain "A.7 Human resource security , which is included in the Annex A of ISO 27001:2013, and is composed by the objective control "A.7.1 Prior to employment", "A.7.2 During employment" and "A.7.3 Termination and change of employment". In some cases, can be also necessary ask to them questions related to legal obligations (domain A.18), if the HR team is responsible for these issues.
So basically you need to ask questions related to the compliant of controls included in the domain A.7.
Finally, this article can be interesting for you How to make an Internal Audit checklist for ISO 27001 / ISO 22301 : https://advisera.com/27001academy/knowledgebase/how-to-make-an-internal-audit-checklist-for-iso-27001-iso-22301/