While seated, have a partner raise the arm of your sore shoulder to the front and overhead as far as possible.
Your partner should use one hand on your arm and the other hand supporting your shoulder blade (scapula).
The space where your rotator cuff tendons and shoulder bursa reside (the sub-acromial space) becomes smaller when your arm is raised overhead and pushed to the limit. If pain is felt in your shoulder, the test is considered positive. The pain is likely caused by impingement of the tendons or bursa in that area of your shoulder.
I did not have a torn cuff, but I did have a good bit of pain which lasted at least 3 months. PT did not help at all. I rested it, but didn't stop using it, and eventually the pain went away. I also had an MRI, which didn't show anything. Back in my paranoid days!
Hope this helps!