Test First, Test Later, Test Never
In this chapter, we are going to review some of the nuances of Test-Driven Development (TDD). We’ve already covered the broad techniques of writing unit tests as part of an overall test strategy. We can use the test pyramid and hexagonal architecture to guide the scope of our tests in terms of what specifically they need to cover.
We have two more dimensions we need to decide on: when and where to start testing. The first question is one of timing. Should we always write our tests before the code? What difference would it make to write tests after the code? In fact, what about not testing at all – does that ever make sense? Where to start testing is another variable to decide. There are two schools of thought when it comes to TDD – testing from the inside out or the outside in. We will review what these terms mean and what impact each has on our work. Finally, we will consider how these approaches work with a hexagonal architecture...
