定義漏れの外部キーを自動検知する

missing_foreign_keys_spec.rb

# frozen_string_literal: true

RSpec.describe 'ActiveRecord foreign key' do
  let(:connection) { ActiveRecord::Base.connection }
  let(:tables) { connection.tables }

  def foreign_key_exists?(reflection, foreign_keys)
    to_table_name = reflection.klass.table_name
    reflection.foreign_key

    foreign_keys.any? do |foreign_key|
      foreign_key.to_table == to_table_name && foreign_key.column == reflection.foreign_key
    end
  end

  # テスト対象外にするテーブル一覧
  # [table_names, ...]
  let(:ignored_tables) do
    %w[]
  end

  it 'detects missing foreign keys' do
    missing_reflections = []

    (tables - ignored_tables).each do |table_name|
      foreign_keys = connection.foreign_keys(table_name)

      class_name = table_name.singularize.classify
      klass = class_name.constantize
      reflections = klass.reflect_on_all_associations(:belongs_to)
      reflections.reject!(&:polymorphic?)

      reflections.each do |reflection|
        next if foreign_key_exists?(reflection, foreign_keys)

        missing_reflections.push(
          [table_name, reflection]
        )
      end
    end

    expect(missing_reflections).to be_empty, -> {
      missing_keys = missing_reflections.map do |(table_name, reflection)|
        "add_foreign_key(:#{table_name}, :#{reflection.klass.table_name})"
      end

      <<~EOS
        Not found foreigin key.
        #{missing_keys.join("\n")}
      EOS
    }
  end
end