Mock Objects

Mock Objects

// Mocking dependencies
class EmailService {
    public function send(string $to, string $subject): bool { /* real implementation */ }
}

class UserService {
    public function __construct(private EmailService $email) {}

    public function register(string $email): bool {
        // ... create user ...
        return $this->email->send($email, "Welcome!");
    }
}

class UserServiceTest extends TestCase {
    public function testRegisterSendsEmail(): void {
        // Create mock
        $emailMock = $this->createMock(EmailService::class);

        // Set expectation
        $emailMock->expects($this->once())
                  ->method("send")
                  ->with("alice@example.com", "Welcome!")
                  ->willReturn(true);

        $service = new UserService($emailMock);
        $result  = $service->register("alice@example.com");

        $this->assertTrue($result);
    }
}