Deleted all code
First test of TDD as you really mean it
Progressed too far - going back after saving
Almost all tests implemented. Take turns left
All tests implemented. Now going to refactoring
Made all methods static
Moved all methods to Game (IntelliJ refactor step)
Revelation simplified code. Columns, rows and diagonals are all just variations of a set of win conditions
Refactored static methods into game object with state
Made final test a part of the game