Database Seeding & Fixture Management

Also Known As

TL;DR

Explanation

Database seeding creates consistent data states for development, testing, and demos. Patterns: Seeders (run once to populate dev/staging), Factories (define blueprints for generating model instances with realistic fake data — Faker library), Fixtures (static data files loaded for tests). Factory best practices: realistic but anonymised data, factory states for different scenarios (admin user, suspended user), and factory relationships. Test databases reset between test runs (DatabaseTransactions or RefreshDatabase) using seeders for required reference data.

Common Misconception

Why It Matters

Common Mistakes

• Seeding production-like volumes in tests — 100,000 seeded rows makes tests slow; seed only what tests need.
• Hardcoded IDs in seeds and factories — brittle tests that break when IDs change.
• No factory states — creating 'admin user' vs 'regular user' via attributes instead of named states.
• Shared database between tests — never share state; each test must reset or use transactions.

Code Examples

// Manual test data in tests — brittle and slow:
class OrderTest extends TestCase {
    public function setUp(): void {
        $pdo->exec("INSERT INTO users VALUES (1, 'Alice', 'alice@example.com')");
        $pdo->exec("INSERT INTO orders VALUES (1, 1, 99.99, 'pending')");
        // ID 1 hardcoded — breaks when other tests run first
    }
}

// Laravel factories — flexible, realistic, relationship-aware:
class UserFactory extends Factory {
    public function definition(): array {
        return [
            'name'     => $this->faker->name(),
            'email'    => $this->faker->unique()->safeEmail(),
            'password' => Hash::make('password'),
        ];
    }
    public function admin(): static {
        return $this->state(['role' => 'admin']);
    }
    public function withOrders(int $count = 3): static {
        return $this->has(Order::factory()->count($count));
    }
}
// Test: one line creates everything needed:
$user = User::factory()->admin()->withOrders(3)->create();

References

• ↗ https://laravel.com/docs/eloquent-factories

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