I want to say "needs a test" but looking at the decorator, there are no existing tests for it where you could have added it. Yet it must be done :) Can you please create an AlterTableDecoratorTest in the same place and same way CreateTableDecoratorTest and add your option in there? (I could assist if unsure how)

Sure, I'll add it to the PR.

Edit: seems like I included more commits than intended, I'll check that first.

Thank you :)

Edit: I am working under assumption that even though overly database specific modifications are usually rejected, since there is already a MySqlAlterTableDecorator, adding to it should not be a problem.

Yes, this is my assumption too.

New test class included, no error detected on PHPUnit on my instance.

@nanawel thanks for your contribution!