The goal here is to practise some TDD skills around the fizzbuzz kata.
This method is probably the most used technique for TDD. The basic idea is to think about the next direction of your program, write a test for it and implement it. This method is usually used when you know well the structure of your program and have a good idea on where to make the change to implement the next feature. You can practise this method with the src/test/java/Triangulation file.
This method consists in writing the test for your next feature, hardcode the result in your program and then refactor it to make it scale. This method is usually used when you are not completely sure where to make the change in your program. You can practise this method with the src/test/java/FakeIt file.