Testing methods called from another method [duplicate]

Question

I have a class with a method called DataIn(int InputID, string CSVValue), this is the main entry point to it.

This method based on the InputID stores the CSV Value parameter into relevant List<string>'s. When the InputID is the same as a property called NoOfRows it then creates one List<string> made up of all the others. It then checks the validity of this final List<string>, if all is ok then it adds the results to a HashSet<int> as a quick way of checking for duplicates.

I have broken this logic into 3 methods so DataIn calls StoreData, when the InputID in DataIn = NoOfRows it calls MergeData which calls ValidateData.

My question is should I make these methods public to test them separately or should I keep them private and pass in data to DataIn and the do asserts on the merged data List<string> and the HashSet<int>. DataIn will be the method that is called from outside the class, making the other methods public would only be for unit testing.

My concern is that if I make the other methods public and test they are ok I am then not testing DataIn works as expected or if I do both I end up with duplicate tests.

What's your advice?

Answer 1

Always stick to the principle of least privilege. Exposing private methods as public just to make them unit testable is not a good design. Instead, stick to testing the public interfaces only. If a method behaves in multiple ways with different inputs, make sure that you write a test per behavior expected and you should a neat and clean design, while still being well tested.