rails test doesn't load initializers when unit testing

I've got some custom inflection rules. One is for 'merk', it lives in 'initialializers/inflections.rb':

ActiveSupport::Inflector.inflections do |inflect| inflect.irregular 'merk', 'merken' end

But when I run rake test:units, I get an error:

test_truth(BrandstofTest): ActiveRecord::StatementInvalid: SQLite3::SQLException: no such table: merks: DELETE FROM "merks" WHERE 1=1

So, I think the custom inflection rules aren't loaded during these unit tests. However, if I go into 'script/console test', these rules work fine!

'merk'.pluralize => "merken"

Merk.delete_all => 0

Merk.table_name => "merken"