let’s say there is a Shape interface.

interface IShape { double Area(); }

A Rectangle class and a Triangle class implement it. Now should i write tests for:

  1. IShape interface and test both implementations in a single test file?
  2. Write tests for Rectangle and Triangle class separately, testing their implementation of Area() ?
  3. Do something else?

From what I see I am testing implementations either ways. How do you even test an interface without testing the implementation? Can someone please help clarify my doubts? Thanks!

  • @abhibeckert
    6•1 year ago

    Is that a real example, or a contrived one?

    I don’t think it’s normal to write a test for IShape.Area() in your example. You’d only write tests for Rectangle.Area() and Triangle.Area().

    Wether or not all of that is in the same file should, in my opinion, depend how many tests there are. If there are “too many” lines of code, split it into multiple files.