[12.x] Fix opened transaction in HTTP tests

[lucasferro0]

Overview

This pull request adds automatic database transaction control during HTTP tests when the DatabaseTransactions trait is used. The implementation ensures that the transaction level is always reset to 1 after each HTTP request in the tests, preventing issues with uncommitted nested transactions. This makes the test scenario more aligned with a real-world scenario where the transaction is rolled back when a "response" is returned.

Before Changes

api.php

Route::post('users', function () {
    DB::beginTransaction();  // Starts nested transaction (level 2)
    
    User::create(['name' => 'John']);
    
    // Forgot to commit or rollback!
    return response()->json(['success' => true]);
});

UserTest.php

class UserTest extends TestCase
{
    use DatabaseTransactions;

    public function test_create_user()
    {
        $response = $this->postJson('/api/users');
        
        // Problem: transaction is still at level 2
        $this->assertDatabaseMissing('users', ['name' => 'John']); // Fails
    }
}

After Changes

api.php

Route::post('users', function () {
    DB::beginTransaction();  // Starts nested transaction (level 2)
    
    User::create(['name' => 'John']);
    
    // Forgot to commit or rollback!
    return response()->json(['success' => true]);
});

UserTest.php

class UserTest extends TestCase
{
    use DatabaseTransactions;

    public function test_create_user_without_commit()
    {
        $response = $this->postJson('/api/users');
        
        // Transaction reset to level 1 automatically
        // Nested transaction rollback was executed
        $this->assertDatabaseMissing('users', ['name' => 'John']); // Passes
    }
}

Reference links

PHP documentation - PDO Transactions

[github-actions]

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[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!