§ 24-6-605 [Judge Prohibited From Testifying at Trial]

The judge running your trial cannot also be a witness in that same trial. These are two separate roles, and one person cannot fill both at the same time.

If a judge tries to testify in a trial they are presiding over, you do not need to formally object to bring this up later. The issue is automatically preserved, meaning you can raise it on appeal without having said anything during the trial.