PHPUnit — Testing

Learning PHPUnit for automated testing. How to run the examples and notes on common patterns to reference from.

How to run tests

• Install PHPUnit as a dev dependency (recommended):

  composer require --dev phpunit/phpunit

• Running tests:

  ./vendor/bin/phpunit [tests/path]

Test file layout and naming

• Tests live under tests/.
• Files/classes should be named SomethingTest.php and test classes SomethingTest to match.
• Each test file will extend on the PHPUnit\Framework\TestCase.

Common assertions

• assertSame(expected, actual) — strict type and value equality
• assertEquals(expected, actual) — loose equality
• assertTrue / assertFalse
• assertNull / assertNotNull
• assertCount(expected, array)
• assertInstanceOf(Class::class, $obj)
• assertStringContainsString(substr, string)

Basic code standards

• Keep tests small and focused (one assertion intent per test when possible).
• assertSame for primitives to avoid type-coercion.
• Use setUp to reduce duplication, but avoid hiding important setup in multiple layers.

Fixtures: setUp / tearDown

• Use the setUp() method to create fixtures used by many tests and tearDown() to clean up.

protected function setUp(): void
{
    // runs before each test
}

protected function tearDown(): void
{
    // runs after each test
}

Grouping tests

• Add @group name to tests and run with --group name to run only that group, see phpunit.xml.dist excluding the group named excluded.

Mocking

• Definition: A programmable stand-in for a real dependency.
• Behavior: Returns exactly what you tell data/errors to isolate your code.

Use Cases

• External Issues: Real service is slow, flaky, or unavailable.
• Simulation: Testing edge cases (errors, timeouts, specific payloads).
• Efficiency: When you need tests to be fast and deterministic.

Why Mock?

• Isolation: Focuses testing on your logic, not external systems.
• Speed: Skips heavy processing and network latency.
• Reliability: Eliminates test flakiness caused by third-party outages.

Tests total not matching

• If PHPUnit cannot find your classes, ensure Composer autoload is configured and run composer dump-autoload.

Offical Docs

• https://phpunit.de/documentation.html