Steps to reproduce

# create a new rails app
rails new rails-helper-init && cd rails-helper-init

# create a resource to play with
rails generate scaffold Ninja

# modify the helper so it has an initializer
echo "module NinjasHelper
  attr_accessor   :initialized_count
  def initialize( *args, &block )
    super *args, &block

    @initialized_count    ||= 0
    @initialized_count    +=  1
  end
end" > app/helpers/ninjas_helper.rb

# create a test that checks the helper is initialized
echo "require 'test_helper'

class NinjasHelperTest < ActionView::TestCase
  def test_initialization_count
    assert_equal initialized_count, 1
  end
end" > test/unit/helpers/ninjas_helper_test.rb


# run migrations
rake db:migrate

# run tests
rake test:units

Expected Behaviour

The above helper unit test should pass.

Actual Behaviour

rake test:units
(in /tmp/rails-helper-init)
Loaded suite /home/davidjh/.rvm/gems/ree-1.8.7-2010.01/gems/rake-0.8.7/lib/rake/rake_test_loader
Started
.F
Finished in 0.013791 seconds.

  1) Failure:
test_initialization_count(NinjasHelperTest) [/test/unit/helpers/ninjas_helper_test.rb:5]:
<nil> expected but was
<1>.

2 tests, 2 assertions, 1 failures, 0 errors
rake aborted!

Notes

This is strictly an issue with testing: the view is initialized properly
(presumably because the initializer of the class that mixes it in calls super) when running rails.

Misc.

[davidjh@nyx (; ree-1.8.7-2010.01)] /tmp/rails-helper-init
$ rails --version
Rails 3.0.0.beta4
[davidjh@nyx (; ree-1.8.7-2010.01)] /tmp/rails-helper-init
$ ruby --version
ruby 1.8.7 (2009-12-24 patchlevel 248) [x86_64-linux], MBARI 0x6770, Ruby Enterprise Edition 2010.01