Testing a db migration in rails 7

I've been trying to write a spec to test a rails migration, but any guides i find online, (e.g. https://nebulab.com/blog/testing-ruby-on-rails-migrations) use the deprecated: ActiveRecord::Migrator.new(:up, migrations, current_version).migrate

what is the equivalent in rails 7?

and has anyone a super simple example of testing a migration in rails 7?

Update: I have a migration which renames a table and the related rails model, removes a column from that table, adds another column, and finally migrates existing entries in that table (new column is populated by looking up info using the column that gets dropped)

I mainly want to test that the existing data gets migrated properly

Here was the new setup for my specs after upgrading to Rails 7.1 which pushed ActiveRecord to 7.1:

  let(:migration_context) { ActiveRecord::MigrationContext.new(ActiveRecord::Migrator.migrations_paths) }
  let(:previous_version) { XX_XXX_XXX_XXX_XXX }
  let(:current_version) { XX_XXX_XXX_XXX_XXX }

Then when I went to run or revert:

  def run_migration
    migration_context.up(current_version)
  end

  def revert_migration
    migration_context.down(previous_version)
  end

According to the docs it seems like I should have been able to pass :up to .run on the context, but I just couldn't get that to trigger the up method in my migration. But the above did the trick. Hope this helps!