We have indicated that the TestAdd(...) method is a test method with a compiler attribute called [Test]. However, in this case, we have added additional information to state that the [TestCaseSource(...)] data source for this method is the AdditionProvider method.
This means that Unity Test Runner will retrieve the data objects from the additional provider and create multiple tests for the TestAdd(...) method, one for each set of data from the AdditionProvider() method.
In the Test Runner window, we can see a line for each of these tests:
TestAdd(0, 0, 0)
TestAdd(1, 0, 1)
TestAdd(0, 1, 1)
TestAdd(1, 1, 2)