The traditional way of writing unit tests. The broken lines represent actions people treat as optional.
Test-driven development—a bird’s-eye view. Notice the spiral nature of the process: write test, write code, refactor, write next test. It shows the incremental nature of TDD: small steps lead to a quality end result.
Taken from: The Art of Unit Testing, Second Edition: with examples in C#. Author:Roy Osherove.