CODEWITHSUNDEEP
ruby-on-railstestingrspectdd
cman77
cman77

Reputation: 1783

Working with test database in rails

I am trying to populate my rails Test database and am running into issues.

I have a script which I use to rest, generate and populate my Development database which works without issue. Basically something like

namespace :db do
  desc "Fill database with sample data"
    task populate: :environment do
      Rake::Task['db:reset'].invoke
      --Create all my dummy data here---
    end
  end
 end

I then run the commands:

bundle exec rake db:populate
bundle exec rake db:test:prepare

The first commands resets and populates my database using the above rake task, but the second command only recreates my data structures and does not populate the data.

I am doing this for some RSPec tests to have access to - but I am wondering if I am approaching this incorrectly? Should I not have ANY test data (only structure) in my test database for TDD? Should everything always run off of Fixtures instead?

Upvotes: 2

Views: 6356

Answers (2)

Sam Peacey
Sam Peacey

Reputation: 6034

but I am wondering if I am approaching this incorrectly? Should I not have ANY test data (only structure) in my test database for TDD? Should everything always run off of Fixtures instead?

In general, yes your test database should be empty - if your test database is populated, and not cleaned between tests, you open yourself up to the possibility of having different test results depending on the order in which tests run.

You can use either fixtures, or more commonly these days, factories to populate data for each test before it's run. Fixtures will populate the whole database from your fixtures file, so for each test, you'll be populating a lot of unnecessary data. With factories, you specify the data to populate in the test itself (specific data and associated records is taken care of by your factory definitions).

A couple of popular factories are factory_girl: https://github.com/thoughtbot/factory_girl and Machinist: https://github.com/notahat/machinist

You will also want something like database_cleaner: https://github.com/bmabey/database_cleaner - database_cleaner takes care of wiping your database between each test so you start the test with a clean slate.

There is a railscast here: http://railscasts.com/episodes/158-factories-not-fixtures with the basics of getting going with factories

Upvotes: 1

Josh Rieken
Josh Rieken

Reputation: 2266

In my experience, it's good practice to not be dependent on running rake tasks or using any other external process to fill in test data. You should do any data loading within the tests themselves and create helpers placed in spec/support to avoid duplication where necessary.

I've seen all kinds of strategies for loading test data: custom seed classes placed in lib, fixtures (though fixtures can be brittle and a pain in certain cases), and more heavyweight solutions such as the factory_girl_rails and fabrication gems, to name just a few.

As for db:test:prepare, it simply "checks for pending migrations and loads the test schema", according to the Rails guide; no actual data is loaded.

http://guides.rubyonrails.org/testing.html#preparing-your-application-for-testing

Hope that helps!

Upvotes: 4

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