RoR Tutorialでpassword_digestのエラーが出た場合の確認項目 ref: http://qiita.com/koka0828/items/4631822d17af1d6a1a5c

file0.txt

rails generate migration \
add_password_digest_to_users password_digest:string

file1.txt

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :name
      t.string :email

      t.timestamps
    end
  end
end

file2.txt

$ bundle exec rake db:migrate