Dislocated shoulder

A 44-year-old man presents to his primary care physician with worsening left shoulder pain. He can no longer do bench presses or shoulder presses at the gym due to weakness and pain. The pain is primarily located over the lateral shoulder, is worse at night, and is preventing him from obtaining adequate rest. Past medical history is otherwise unremarkable. He has no history of recent trauma or surgeries to the left shoulder. The patient subsequently undergoes a MRI of the left shoulder, which reveals the following:  


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Which of the following physical examination maneuvers is most likely to yield a positive test, given this patient’s clinical findings?