This document introduces test-driven development (TDD) and unit testing using PHPUnit. It discusses the benefits of unit testing, including reducing bugs, improving code design and documentation. It then demonstrates using TDD to build a simple calculator application, showing how to set up a PHP project with PHPUnit, write tests that initially fail and then pass as code is added, and refactor code. The full source code for the calculator tests and class are provided.

1. Test Driven Development with PHPUNIT
Tuan Nguyen, Full Stack Developer
Welcome

2. Background and Motivation - My Background
Tuan Nguyen
• 7+ years of experience in web development
• Recent position: Software development team lead
• Recent project: Enterprise Content Management System

3. Background and Motivation - Unit Testing
Most of the developers (I know) don’t like Unit Testing. Why?
• “Not having enough time”
• “I understood the requirements and I have implemented them
carefully in the code”
• “This part is not so important”
• “I am lazy”

4. Background and Motivation - Unit Testing
Benefits of unit testing
• Unit Tests reduce bugs
• Unit Tests are good documentation
• Unit Tests improve design
• Unit Tests prove your code actually works
• Unit Test are vital to regression testing

5. Background and Motivation - Unit Testing
Unit test is a requirement for Software Engineer

6. Workflow of TDD and Unit Test
3 Laws of TDD
• Create a test that fails
• Write code to pass the test
• Clean up the code

7. Demonstration of TDD and Unit Test
The problem to solve
Build a simple calculator with four functions: adding, subtracting,
multiplying and dividing. [5]

8. Demonstration of TDD and Unit Test
The tools we need
• MAMP - Virtual web servers on local machine
• PHP Composer - Manage open source PHP libraries
• PHPUnit - PHP test frameworks
• Sublime Text - Development-friendly text editor

9. Demonstration of TDD and Unit Test
Create a project

10. Demonstration of TDD and Unit Test
Install PHPUnit

11. Demonstration of TDD and Unit Test
Installed PHPUnit in vendor folder

12. Demonstration of TDD and Unit Test
CalculatorTest.php file with first test case

13. Demonstration of TDD and Unit Test
First test doesn’t pass

14. Demonstration of TDD and Unit Test
Create class Calculator.php to pass the test

15. Demonstration of TDD and Unit Test
setup() and tearDown() function in PHPUnit

16. Demonstration of TDD and Unit Test
The first real test - testAdd()

17. Demonstration of TDD and Unit Test
Write code to pass the test - add() function with bug

18. Demonstration of TDD and Unit Test
Test result of add() function with bug

19. Demonstration of TDD and Unit Test
Fix the bug to pass the test

20. Demonstration of TDD and Unit Test
Pass the test for add() function

21. Demonstration of TDD and Unit Test
Apply these steps for other functions: subtract(), multiply(),
divide()
• Full source of CalculatorTest.php - http://pastebin.com/pAFAZJDC
• Full source of Calculator.php - http://pastebin.com/zXhiVLR8

22. References
[1] Top 12 Reasons to Write Unit Tests, http://www.onjava.com/pub/a/onjava/2003/04/02/javaxpckbk.html
[2] Unit testing: Why bother?, http://soundsoftware.ac.uk/unit-testing-why-bother/
[3] The Cycles of TDD, http://blog.cleancoder.com/uncle-bob/2014/12/17/TheCyclesOfTDD.html
[4] Test Driven Development (TDD) using PHPUnit, http://diogoosorio.com/blog/test-driven-development-tdd-
using-phpunit
[5] Test Driven Development With PHP, https://paulund.co.uk/test-driven-development-with-php
[6] Let's TDD a Simple App in PHP, http://code.tutsplus.com/tutorials/lets-tdd-a-simple-app-in-php--net-26186

23. Thank You!
Tuan Nguyen, nganhtuan63@gmail.com