How to test ActiveRecord witout Rails?

问题

I have a project in which I use ActiveRecord to store information in a sqlite db file. I'm not using Rails and AR seems to do the job perfectly. My question is how exactly to test my classes witout hitting the db? I found some gems that would to the trick (FactoryGirl, UnitRecord), but they are meant to work with Rails.

class News < ActiveRecord::Base
belongs_to :feed

def delete_old_news_if_necessary
  # time_limit = Settings::time_limit
  return if time_limit.zero?

  News.destroy_all("date < #{time_limit}")
end

def delete_news_for_feed(feed_id)
  News.destroy_all(:id => feed_id)
end

def news_for_feed(feed_id)
  News.find(feed_id)
end
end

I read that i can do a column stub:

Column = ActiveRecord::ConnectionAdapters::Column
News.stubs(:columns).returns([Column.new(),...])

Is this the right way to do these tests? Also, when is it better to have a separate db just for testing and to create it, run the tests, and the delete it?

回答1:

If you want to avoid hitting the db in tests I can recommend the mocha gem. It does stubs as well as it lets you define expectations.

Edit: Regarding your question on when it is better to use a test db: I would say, whenever there is no reason against it. :)

Edit: For example, you can mock News.find like this in a test:

def news_for_feed_test
  # define your expectations:
  news = News.new
  News.expects(:find).with(1).returns(news)
  # call the method to be tested:
  News.new.news_for_feed(1)
end

At the same time this makes sure, find gets called exactly once. There are a lot more things Mocha can do for you. Take a look at the documentation. Btw., it looks like these methods of yours should be class methods, no?

来源：https://stackoverflow.com/questions/14750959/how-to-test-activerecord-witout-rails