Because you have a global semaphore which is initialized with 10, it is very hard to see the relationship betwen 1+ 9 licenses acquired is a success. If you initialize the semaphore within this method and make a local variable 'initalPermitCount=10' or something, you can do

    assertTrue(semaphore.tryAcquire());
    assertTrue(semaphore.tryAcquire(initialPermitCount-1));

Then it become a lot easier to understand what the relationship is with the initial permit count.