如何使用 Minitest 对私有方法进行单元测试

Question

I wanted to test a private method but I came across an answer that states simply YOU DONT!

How can I refactor this code so that I can test it?

In my controller, I have a private method

 def move_employees
    return unless params[:store_id].present?
    store = scope.find(params[:store_id])
    store.employments << @store.employments
    store.save!
 end

This method is called inside the destroy action such that when I want to delete a store that has employees, I can move them over to an existing store picked from an drop down menu

def destroy
    @store = scope.find(params[:id])
    authorize([:manage, :settings, @store])
    if @store.destroy
        move_employees
...

I am thinking of moving the method to the model, but I am not sure if that is the best approach, and also, I don't know how I would then test it.

What is the best practice in this case?

Thank you.

Answer 1

Philosophically, you shouldn't, as private methods are expected to be tested in the context of the public code. For example, if move_employees must be called as part of destroy , test the end state, not the mechanism to get there. That is, assert that after deletion the employees are correctly moved.

Practically you can test directly if you're prepared to bust out send . This more direct method of testing can be useful for particularly complex implementations, but in those cases you should probably separate your concerns and have some other tool that facilitates that operation which does have a public interface.