[8.x] Close doctrineConnection on disconnect

[lcharette]

Consider this test:

class ExampleTest extends TestCase
{
    use DatabaseMigrations; 

    protected function tearDown(): void
    {
        // parent::tearDown(); <-- Omitted on purposed (or not)

        DB::disconnect();
    }

    public function test_1()
    {
        $this->assertTrue(true);
    }

    public function test_2()
    {
        $this->assertTrue(true);
    }

    // Repeat test 102x times...

    public function test_105()
    {
        $this->assertTrue(true);
    }
}

With a migration that modify a column:

public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->increments('id');
        $table->string('user_name', 50);
    });

    Schema::table('users', function (Blueprint $table) {
        $table->string('user_name', 120)->change();
    });
}

On PostgreSQL, after the 100th iteration, this error will pop up:

Illuminate\Database\QueryException: SQLSTATE[08006] [7] connection to server at "127.0.0.1", port 5432 failed: FATAL:  sorry, too many clients already (SQL: create table "migrations" ("id" serial primary key not null, "migration" varchar(255) not null, "batch" integer not null))

While disconnect sets the “main” PDO object as null, the Doctrine connection created by the “change” action is not. The actual connection to the database is not actually closed in this specific case as the underlying PDO object is not fully destroyed as per PHP Documentation: https://www.php.net/manual/en/pdo.connections.php.

This bug won't affect any migration that are not modifying a column, as the Doctrine Connection is only created when needed, eg. using ->change().

I understand this fix won’t have much impact on a normal Laravel install, as :

1. Laravel TestCase undefined the whole app on tearDown(), Connection included, closing the Doctrine connection.
2. This test is pointless and should call parent::tearDown();

But in a situation where disconnect() is called outside of a test scenario, or anyone not using the whole Laravel TestCase might encounter this issue.

References :

• Postgre "too many clients already" on running tests #18056
• PDO Too many connections when running test suite #18471
• [5.4] Fix 'Too Many Connections' error during testing using $connectionsToTransact #20340