tootlab-mastodon/spec/fabricators/account_fabricator.rb

keypair     = OpenSSL::PKey::RSA.new(2048)
public_key  = keypair.public_key.to_pem
private_key = keypair.to_pem

Fabricator(:account) do
  username            { sequence(:username) { |i| "#{Faker::Internet.user_name(nil, %w(_))}#{i}" } }
  last_webfingered_at { Time.now.utc }
  public_key          { public_key }
  private_key         { private_key}
end