Testing PHP APIs with PHPUnit Data Providers

PHPUnit data providers run a test method against several named input and expected-output cases.

What It Does

PHPUnit data providers run a test method against several named input and expected-output cases. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

A local Composer project with a compatible PHPUnit version and isolated fixtures or stubs.

Unit tests use isolated dependencies, while feature, contract and integration tests cover real HTTP or database behavior.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Use a version of PHPUnit compatible with your PHP runtime.

composer require --dev phpunit/phpunit

This is a command-line example; use it in its appropriate file or shell, not in the PHP source editor.

Example 2: Another Case

PHPUnit attributes associate a public static data provider with a test.

<?php
use PHPUnit\Framework\Attributes\DataProvider;
use PHPUnit\Framework\TestCase;
final class DiscountTest extends TestCase {
    public static function cases(): iterable {
        yield 'none' => [100, 0, 100];
        yield 'ten percent' => [100, 10, 90];
    }
    #[DataProvider('cases')]
    public function testDiscount(int $price, int $percent, int $expected): void {
        self::assertSame($expected, intdiv($price * (100 - $percent), 100));
    }
}

This example depends on an installed extension, third-party library or configured service and is not a standalone local test.

Practical Example: Putting It to Use

Run the selected test in a project with PHPUnit autoloaded.

vendor/bin/phpunit --filter DiscountTest

This is a command-line example; use it in its appropriate file or shell, not in the PHP source editor.

Important Behavior and Edge Cases

The provider must match the PHPUnit version and expected static signature.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• PHPUnit data providers run a test method against several named input and expected-output cases.
• The provider must match the PHPUnit version and expected static signature.
• Keep each case independent and give failing cases descriptive labels.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.