Improving Database Transaction Handling in Tests

Introduction

During recent testing of the social login functionality in our application, we encountered intermittent failures. These "flaky" tests were traced back to how database transactions were being handled, particularly in PostgreSQL.

The Challenge

The core issue was that within a test, a failed database query (e.g., due to a validation error during profile synchronization) would abort the entire transaction in PostgreSQL. While the PHP exception was caught by a try-catch block, the underlying database transaction remained in a failed state. Subsequent assertions that relied on the database state would then fail, leading to inconsistent test results.

The Solution

To address this, we wrapped the profile synchronization queries within a DB::transaction() block to create savepoints. Savepoints allow us to isolate failures within a transaction, so a failed query only rolls back to the savepoint, not the entire transaction. This ensures that the outer test transaction remains alive, even if an inner query fails.

use Illuminate\Support\Facades\DB;

class SocialProfileService
{
    public function syncProfile(User $user, array $profileData)
    {
        DB::transaction(function () use ($user, $profileData) {
            try {
                $user->updateProfile($profileData);
                // Additional synchronization logic here
            } catch (\Exception $e) {
                // Handle the exception (e.g., log it)
                throw $e; // Re-throw the exception to propagate it
            }
        });
    }
}

Key Decisions

1. Using DB::transaction() for Savepoints: This provides a clear and concise way to define savepoints around critical database operations.
2. Exception Handling: The try-catch block allows us to handle exceptions gracefully without aborting the entire test.

Results

• Eliminated flaky tests related to social login functionality.
• Improved the reliability and stability of our test suite.
• Ensured that database transactions are properly handled in PostgreSQL, preventing unexpected failures.

Lessons Learned

This experience highlighted the importance of understanding database-specific transaction behavior, especially when using different database systems in development and production. Using savepoints provides a robust mechanism for handling errors and ensuring data consistency in complex database operations.