PHPUnit – Unit Testing with PHP

Unit TestingIn modern software development, unit testing can no longer be an ignored activity, especially for object oriented programming (OOP). I have been coding in PHP for several years now. I thought I’d share my thoughts on unit testing in PHP with you.

Unit Testing in PHP

OOP has so many advantages over procedural programming and unit testing is one of them. I’m not saying that unit testing can’t be done with procedural styles, but it has a much better use case in OOP programming. I am not going to get into the nuts and bolts of setting up PHPUnit for your PHP project, but JetBrains, the folks behind my favorite IDE for PHP, have an excellent article about setting up PHPUnit for PhpStorm. It can be found here.

Once PHPUnit is set up, writing tests is easy. Just plug in what you want to send to a method and tell PHPUnit what you expect the results to be.

Skeleton Framework

Here is a basic skeleton framework for writing tests.


 * Created by PhpStorm.
 * User: aaron
 * Date: 8/13/17
 * Time: 12:03 PM

require '../lib/Utilities/Utilities.php';

class UtilitiesTest extends PHPUnit_Framework_TestCase {

/* ** Test Initialization ** */

private $utilities;

protected function setUp()
  $this->utilities = new Utilities();

protected function tearDown()
  $this->utilities = NULL;

/* ** Tests ** */

/* ** addTwoNumbers() Tests ** */

public function test_addTwoNumbers() {

  $number1 = 2;
  $number2 = 3;

  $result = $this->utilities->addTwoNumbers($number1, $number2);

  $this->assertEquals(5, $result);


/* ** subtractTwoNumbers() Tests ** */

public function test_subtractTwoNumbers() {

  $number1 = 2;
  $number2 = 6;

  $result = $this->utilities->subtractTwoNumbers($number1, $number2);

  $this->assertEquals(-4, $result);



PHP Assertions

There are a whole slew of assertions built into PHPUnit, assertEquals() is just one of them. Assertions such as assertNull(), assertNotNull(), assertContains() are some of the most common ones used. For a complete list, check out the assertions link of the PHPUnit documentation.

See, that really is pretty simple. Of course, when writing unit tests, there is a danger for the mind to wander and think of ‘what if’ scenarios, especially if you come from a quality background such as a QA Analyst. Unit tests should cover the functionality of the component being tested and nothing else; that is what QA is for; they will find the functional defects, you just need to make sure your code works as expected. That is where the unit tests shine.

The Purpose of Unit Testing

This can’t be stressed enough, the primary purpose of unit tests are not to find defects, they just make sure that the components of code work as they should. Even though the unit tests will find a defect in the above examples if it shows that 2 + 3 = 4, that is not the purpose of the test as this will be found during functional testing. The purpose is just to make sure that the method works correctly; calculator examples are also the easiest examples to demonstrate code.