PHPUnit

To install phpunit framework make sure you have installed composer
If not follow instructions from this link http://codeinsightacademy.com/blog/php/composer/

Installation

Install php-xml
As we are going to use phpunit.xml we need to install php-xml

sudo apt install php-xml
#To install specific version
sudo apt install php7.4-xml

Install mbstring

sudo apt-get install php-mbstring

Create composer.json file in project root directory

{
"autoload" : {}
}

Run one of the composer command

composer dump-autoload -o
OR
composer update

Install sluggable

composer require cviebrock/eloquent-sluggable

Install intl
This is required when you are using Code Igniter framework

apt-get install php-intl
#OR specific version
apt-get install php7.4-intl

Install php unit framework

composer require phpunit/phpunit ^9

Create function

global_functions.php

<?php

function add($x = 0, $y = 0) {
        return $x + $y;
}

index.php

<?php

require_once("vendor/autoload.php");

echo add(5, 6);

composer.json

{
    "autoload": {
            "files": ["global_functions.php"]
    },
    "require": {
        "cviebrock/eloquent-sluggable": "^8.0",
        "phpunit/phpunit": "^9"
    }
}

Run index.php file

php index.php

Write Testcase

phpunit.xml

<?xml version="1.0" encoding="UTF-8"?>

<phpunit bootstrap = "vendor/autoload.php"
 colors = "true">
    <testsuites>
        <testsuite name="Sample test suite">
            <directory>tests</directory>
        </testsuite>
    </testsuites>

</phpunit>

tests/GlobalFunctionsTest.php
NOTE: MAKE SURE TO GIVE test PREFIX TO YOUR TEST FUNCTION

<?php

class GlobalFunctionsTest extends \PHPUnit\Framework\TestCase {
        public function testAdd() {
                $result = add(5, 6);
                $this->assertEquals(11, $result);
        }
}

Get all assertions functions from here
https://phpunit.readthedocs.io/en/9.5/assertions.html

Run TestCase from root directory

./vendor/bin/phpunit

./vendor/bin/phpunit --testdox

project directory structure

tree -I "vendor"