Feature: nested transactions

[defunctl]

Main Changes

Adds support for nested database transactions. Using DB::beginTransaction() with other existing transactions causes MySQL/MariaDB to commit all existing transactions when it encounters a START TRANSACTION.

Instead, we now properly create savepoints and restore them when utilizing more than 1 transaction. This is similar to what Laravel does for their lockForTransaction functionality.

As wp-browser starts transactions as well, this allows us to start and rollback and initial transaction in tests, so we're creating savepoints instead of committing all of wp-browsers previous transactions in tests:

<?php declare( strict_types=1 );

namespace StellarWP\Licensing\Test\Classes;

use lucatume\WPBrowser\TestCase\WPTestCase;
use StellarWP\Licensing\StellarWP\DB\DB;

/**
 * @mixin \Codeception\Test\Unit
 * @mixin \PHPUnit\Framework\TestCase
 */
class TestCase extends WPTestCase {

	protected function setUp(): void {
		parent::setUp();

		/*
		 * The WP test framework starts a transaction via raw $wpdb->query('START TRANSACTION'),
		 * which the DB facade's depth counter doesn't see. Re-start through the facade so that
		 * any code calling DB::beginTransaction() creates a savepoint instead of implicitly
		 * committing the framework's transaction.
		 */
		DB::beginTransaction();
	}

	protected function tearDown(): void {
		DB::rollback();

		parent::tearDown();
	}
}

[defunctl]

Edit: hold on, still testing some things.

Edit again: It's good.

[shvlv]

I'm really afraid of transactions in the WordPress context because of 100+ different plugins doing something in the DB, but we have it already, and it's a nice improvement. It should be a consumer's responsibility to use this carefully.

[shvlv]

This filename is odd. I think transaction is a single word 😄

[defunctl]

Good call

[johnhooks]

I agree with @shvlv, user beware.

I approve.

I was playing with something similar. I had trouble with WP-Browser and testing logic that used transactions because of the transaction that WP-Browser wraps around the test.

I accounted for it (or another plugin using transactions) with:

SELECT @@in_transaction;

But I knew I was running a newer database and it was available.