class ActiveRecord::ConnectionAdapters::SQLite3Adapter

def self.database_exists?(config)
  config = config.symbolize_keys
  if config[:database] == ":memory:"
    true
  else
    database_file = defined?(Rails.root) ? File.expand_path(config[:database], Rails.root) : config[:database]
    File.exist?(database_file)
  end
end