This document provides an introduction to test-driven development (TDD), including its goals, benefits, and challenges. TDD is an iterative, test-first approach to development where functionality and behavior are defined by tests. Tests are written before code and define the desired API and design. Benefits of TDD include reduced defects, increased initial development time, and easier refactoring and collaboration. Adopting TDD requires practice and a focus on good design principles like separation of concerns.

1. An Introduction to Test Driven Development Michael Denomy Nashua Scrum Club January 13, 2011 www.mdenomy.wordpress.com

7. Red-Green-Refactor

8. TDD In Action Banking User Stories Open Account As a customer, I want to open a bank account with an initial deposit >= 0 dollars. After opening the account, the account balance should be the amount of the initial deposit. Deposit Funds As a customer, I want make a deposit into a bank account. After the deposit, the account balance should be the previous balance plus the amount of the deposit. The deposit amount must be >= 0 dollars Let's write some code

14. TDD and Design What Others Have To Say If TDD has never led you to an unexpected design, you've got more to learn @JoshuaKerievsky The act of writing a unit test is more an act of design than of verification. It is also more an act of documentation than of verification Bob Martin, “Uncle Bob” ...you're always thinking about design. Either you're deciding which test you're going to write next, which is an interface design process, or you're deciding how to refactor, which is a code design process. James Shore

21. An Introduction to Test Driven Development Michael Denomy Nashua Scrum Club January 13, 2011 www.mdenomy.wordpress.com