TDD: A Pragmatic Approach A PRACTICAL GUIDE TO TEST DRIVEN DEVELOPMENT

John Callaway • Professional developer since 1999 • Specialize in web technologies • Primarily with line-of-business • Enjoy learning new tech

What is Test Driven Development Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: requirements are turned into very specific test cases, then the software is improved to pass the new tests, only. This is opposed to software development that allows software to be added that isn't proven to meet requirements.

Kent Beck says: Clean code that works – now. This is the seeming contradiction that lies behind much of the pain of programming. Test Driven Development replies to this contradiction with a paradox – test the program before you write it.

Show of hands • Who writes at least one test a day? • Who writes at least 10 tests a day? • Who writes at least 100 tests a day? • Who will not write a line of production code without a failing test?

Why would we test? • Reduce effort of manual testing • Reduce bug count • Ensure some level of correctness • Remove the fear of refactoring

Why don’t we test? • Testing is hard • Testing takes time • Testing is expensive • We don’t know how

Never have I ever • Used QA as a debugger • Shipped code without verifying it worked • Struggled to reproduce a bug • Cost my company/client money with a defect

What is testable code? • Loosely coupled • Properly segmented • Independent • SOLID

Let’s see some code!

TDD: A Pragmatic Approach John Callaway @matsubonsai www.1north.com

Appendix Wiki - https://en.wikipedia.org/wiki/Test-driven_development Kent Beck - https://en.wikiquote.org/wiki/Kent_Beck Code samples - https://github.com/ovation22/PragmaticTDD Homework: • Add more to Horse detail page • Add Colors page listing all colors • Add Color detail page listing all horses of selected color