SUT
System Under Test の頭字語。テストの対象となるシステムのこと。
Whatever thing we are testing. The SUT is always defined from the perspective of the test. When we are writing unit tests, the SUT is whatever class (also known as CUT), object (also known as OUT), or method (also known as MUT) we are testing; when we are writing customer tests, the SUT is probably the entire application (also known as AUT) or at least a major subsystem of it. The parts of the application that we are not verifying in this particular test may still be involved as a depended-on component (DOC). 参考