As we discussed earlier, in the real world, we can't test every repeatedly after every major feature or change. We can try but we are human and we can miss out on that. The bigger problem is that we may sometimes think that we tested it but miss it and because there is no record of what we tested, we can't know. If we have a separate quality assurance team or person, they will most probably test and keep a record of that. However, in case of a RESTful web service, it will take more of their time or the possibility is that the QA person will test the end product as a whole and not RESTful web service.
Just like the RESTful web service works as one component or one side of a product, there are more low-level components of the RESTful web service as well. Not just endpoints but those endpoints depends on more low-level code. So in order to make our debugging easier, we write tests for these low-level components as well. Also, this way we can ensure that these low...