If PHP has a testing standard, it's PHPUnit. For well over a decade it has been the framework that unit and integration testing in PHP is built on - the assertions, the test-case model, the mocking, the data providers that nearly every other PHP testing tool either extends or interoperates with. Drupal's own test infrastructure is built on it, which makes it the natural foundation for testing anything in this ecosystem.
The Familiar Test-Case Model
A test extends a base case, and methods assert expected outcomes:
final class NormalizeTest extends TestCase {
public function testTitleIsExtracted(): void {
$tool = normalize($this->node);
$this->assertSame('Repomix', $tool->title);
}
}
Batteries Included
PHPUnit brings a deep assertion library, test doubles and mocks, data providers for parameterized tests, code-coverage reporting, and fixtures for setup and teardown. It's not the flashiest syntax, but it's comprehensive, stable, and understood by every PHP developer - which is exactly what you want from the base layer of your test suite.
Rough Edges and Limitations
- Verbose by modern tastes. The class-and-method ceremony is why wrappers like Pest exist.
- Version discipline. Major versions change APIs; match the version to your framework's requirements.
- Setup for integration tests. Testing framework-integrated code (like Drupal) needs the right base classes and bootstrapping.
Whether you write PHPUnit directly or through a friendlier layer, it's the foundation - and knowing it is part of testing any serious PHP project.
Internal link suggestion: link "a friendlier layer" to the Pest post, which builds on PHPUnit.