How to load db:seed data into test database automatically?

Question

The db:seed rake task primarily just loads the db/seeds.rb script. Therefore just execute that file to load the data.

load "#{Rails.root}/db/seeds.rb"

# or

Rails.application.load_seed

Where to place that depends on what testing framework you are using and whether you want it to be loaded before every test or just once at the beginning. You could put it in a setup call or in a test_helper.rb file.

I'd say it should be

namespace :db do
  namespace :test do
    task :prepare => :environment do
      Rake::Task["db:seed"].invoke
    end
  end
end

Because db:test:load is not executed if you have config.active_record.schema_format = :sql (db:test:clone_structure is)

Putting something like this in lib/tasks/test_seed.rake should invoke the seed task after db:test:load:

namespace :db do
  namespace :test do
    task :load => :environment do
      Rake::Task["db:seed"].invoke
    end
  end
end

I believe Steve's comment above should be the correct answer. You can use Rails.application.load_seed to load seed data into your test envoironment. However, when and how often this data is loaded depends on a few things:

Using Minitest

There is no convenient way to run this file once before all tests (see this Github issue). You'll need to load the data once before each test, likely in the setup method of your test files:

# test/models/my_model_test.rb
class LevelTest < ActiveSupport::TestCase

  def setup
    Rails.application.load_seed
  end

  # tests here...

end

Using RSpec

Use RSpec's before(:all) method to load seed data for all test for this model:

describe MyModel do
  before(:all) do
  Rails.application.load_seed
end

describe "my model..." do
  # your tests here
end

Hope this helps.

We're invoking db:seed as a part of db:test:prepare, with:

Rake::Task["db:seed"].invoke

That way, the seed data is loaded once for the entire test run, and not once per test class.