How to unit test private methods in BDD / TDD?

Question

I am trying to program according to Behavior Driven Development, which states that no line of code should be written without writing failing unit test first.

My ques

Answer 1

If a private method method exists, it's there to be used by a public method. Therefore I'd write a test for the public method.

I write my tests to test the public parts of a class. If the class is well designed then the private parts get tested by default.

If the private method isn't called from a public method, then why does it exist?

In your case I'd do the following

* Write failing test for the public method
* Write public method that calls the private method that doesn't exist yet(test still fails as your class is incomplete
* Write the private method
* Test should now pass