Apologies if this question has been asked before, I've seen similar questions, but nothing quite the same.
I am writing a web application which uses http calls to write and read from a back end database, as well as performing operations on the data.
All of my public methods are along the lines of:
I would like to unit test my performOperationsOnData() method logic, but this is a private method, because it never needs to be called from outside the class.
I have written integration tests, which check that the data is written correctly to the database in general, but when the logic is reasonably complicated I don't really want to be connecting to the database or a mock for every possible path through the logic.
What would be the correct way to test this logic? I am particularly interested in finding out if the structure of the method I have shown should be done differently to make it more testable, or is the answer just lots of mocking and dependency injection for the database?