Sadly we haven't yet introduced the concept of test subjects anywhere else in the guides that I've noticed. You might want to explain what a test subject means, or link to an explanation of what it is. Something along the lines of "A test subject is simply an instance of the object that a particular test is making assertions about. Usually test subjects are manually created by the writer of the test."

You might also want to revise this **slightly** to say: "automatically create test subjects for you, so you don't have to, using the"...