Professional Ruby on Rails™

6.3. Testing a Legacy Database with Fixtures

As previously mentioned, when you go against Rails defaults by adding a legacy database, you lose some of Rails automatic generation magic. One thing that becomes a little bit harder is using fixtures in your unit and automated tests. The standard fixtures method call (which technically is a class method added by Rails to the TestUnit class) assumes that it will be working with the database defined for the test environment. Your secondary database, defined as ingredient_test, is somewhat out of luck. Fortunately, there is a workaround that allows you to have all the functionality of Rails fixtures, and most, if not all, of the convenience that you have when working in a Rails database.

Among the conveniences you give up are the nice little Rake tasks that automatically prepare your test database based on the schema of the development database. You'll need to go in manually to create the test database. You might want to invest the time to create a shell script and/or a Rake task to create your legacy database automatically. Usually that's going to be something like this:

mysql legacy_database < schema.sql

If you do declare this as a Rake task, you can add it as a dependency to the existing test:prepare style tasks like this:

namespace :db do
  namespace :test do
    task :legacy_prepare do
      sh my_load_test_script
    end

    task :prepare => :legacy_prepare
  end
end

Put something like that in your lib/tasks directory, and the Rake db:test:prepare task ...