This document discusses test-driven development and unit testing in ABAP. It defines unit testing as testing individual units or modules of source code to determine if they are fit for use. It defines test-driven development as a process where test cases are created based on requirements first, before developing the software to pass those tests. This helps create simple code designs and improves confidence. The document discusses different types of testing techniques and how to implement unit testing in ABAP using ABAP Unit and executing tests in the SAP GUI or Eclipse. It provides an overview of the test-driven development process of writing a test, making it fail, writing code to pass the test, and refactoring and improving the code and tests.