How to get started Unit testing with PHPUnit

Unit testing is an essential part of any software development process, as it helps to ensure that individual units of code are working as expected. PHPUnit is a popular testing framework for PHP that makes it easy to write and execute unit tests.

In this guide, we will cover the basics of getting started with PHPUnit and writing your first unit test.

Step 1: Install PHPUnit

The first step to getting started with PHPUnit is to install it on your local machine. PHPUnit can be installed using Composer, which is a package manager for PHP.

To install PHPUnit, open your terminal and navigate to your project directory. Then, run the following command:

composer require --dev phpunit/phpunit

This command will download and install PHPUnit as a development dependency of your project.

Step 2: Create a Test Class

Once PHPUnit is installed, you can start writing your first unit test. In PHPUnit, tests are organized into classes, and each test is a method within the class.

Create a new file in your project directory called MyClassTest.php. In this file, define a new class called MyClassTest that extends the PHPUnit\Framework\TestCase class:

use PHPUnit\Framework\TestCase;

class MyClassTest extends TestCase
    // ...

Step 3: Write a Test Method

Next, you can write your first test method. In PHPUnit, test methods must start with the word test, and they should test a specific behavior of your code.

Here’s an example of a simple test method that checks whether the add() method of a hypothetical MyClass class works correctly:

public function testAdd()
    $myClass = new MyClass();

    $result = $myClass->add(2, 2);

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

In this method, we create a new instance of the MyClass class and call its add() method with two arguments. We then use the assertEquals() method to assert that the result of the add() method is equal to 4.

Step 4: Run Your Tests

Now that you have written your first test method, you can run it to see if it passes. In your terminal, navigate to your project directory and run the following command:

vendor/bin/phpunit MyClassTest.php

This command will run the MyClassTest class and output the results of the test.

If the test passes, you should see a message like this:

OK (1 test, 1 assertion)

If the test fails, PHPUnit will output an error message that explains what went wrong.

Step 5: Write More Tests

Once you have written and run your first test, you can continue writing more tests for your code. It’s a good practice to write a test for each behavior of your code to ensure that everything is working as expected.

You can also use PHPUnit’s other assertion methods to test different aspects of your code, such as whether an exception is thrown or whether a certain condition is met.


PHPUnit is a powerful testing framework for PHP that makes it easy to write and execute unit tests. By following the above steps, you can get started with writing your own unit tests and ensure that your code is working as expected. Remember, unit testing is an essential part of the software development process, so don’t overlook it in your own projects!