Added PHPUnit For Testing Purposes

[zaimazhar]

Added PHPUnit base tests for client and category

• Base test cases for future addition. This PR corresponds to No unit test #3 for code consolidation and enhancement.

Versioning

• PHP: 8.0.15
• PHPUnit: ^9

Ongoing Issue

• Most tests require requests to ToyyibPay's API, thus making it harder to mock both successful and failed tests without pasting your API key directly in the test files. My current solution to this issue would be making a config file to paste your API key in tests/config.php

Running Test

./vendor/bin/phpunit --bootstrap tests/config.php tests --testdox

Expected Result

[zaimazhar]

Suggesting to make a dev branch for pull requests before pushing directly into main or master(yeet) branch.

[xputerax]

LMAO baru perasan. Thanks will review it