Question

I am developing an interpreter for a graphical language that I am designing, and I want to apply TDD to my development process (all code in java). My interpreter has only one public function: execute() that executes the a given diagram. To execute the diagram, the class should use a number of internal (private) methods. I want to create these methods using TDD but since they are private I can’t think of a way to access them. What am I doing wrong?

Thanks

Answer 1

1. Are the private functions complex enough that they need their own tests (i.e. multiple tests for execute won’t cover them) ? If yes, maybe you need to break them out into collaborators especially if there are too many private methods. Writing tests against private methods will also hurt future refactoring i.e. let’s say you merge/split some private functions, you’d have a bunch of tests to update even if the functionality for Execute() is still intact.
2. If not, just write as many tests for Execute() as needed to achieve desired confidence/path coverage