minitest-parallel_fork setup for ActiveRecord

test_helper.rb

  Minitest.before_parallel_fork do
    defined?(ActiveRecord::Base) and
      ActiveRecord::Base.connection.disconnect!
  end

  Minitest.after_parallel_fork do |i|
    if defined?(ActiveRecord::Base)
      db_config = Rails.application.config.database_configuration[Rails.env].clone
      db_config['database'] += (i+1).to_s
      ActiveRecord::Base.establish_connection(db_config)
    end
  end