Helper Module Testing

First and foremost

sudo gem install ZenTest

Then in your app/test/test_helper.rb add

require 'test/rails'

Then make a test class

class FooHelper
  def print_hello_world
    content_tag('p', 'Hello World!')
  end
end

class FooHelperTest < Test::Rails::HelperTestCase
  def test_method_goes_here
    assert_equal '<p>Hello World</p>', print_hello_world
  end
end

Of particular note, the name of the class that inherits from Test::Rails::HelperTestCase is very important. If the inheriting class name is MyHelperTest, make sure a module named MyHelper exists.