I have an infection but my wounds heal slowly. i think i have a weak immune system? any tests for that?

Wound healing: Note that there are many factors why a particular wound would not heal as fast as expected; these may have nothing to do with a 'weak' immune system. The immunodeficiency disorders, relatively speaking, are uncommon. On the other hand, disorders like diabetes mellitus which can affect healing, are extremely common. Reviewing this issue with your doctor can lead to specific testing.

May be: Several causes for poor healing of wounds, like age , obesity, untreated infections, poor circulation to the area, recurrent damage to the same area due to nerve damage, poorly controlled diabetes, location of wound like on a bony surface, autoimmune diseases, poor nutrition, lack of vitamins especially vit c, need right diagnosis to treat, see a wound care expert