Run specs/tests multiple times through different gem versions
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Ginger is a small gem that allows you to test your projects using multiple versions of gem libraries. The idea is from Ian White’s garlic – hence the related name of this – but my approach is a bit different, since I don’t test my plugins from within a rails application. Maybe they can be merged at some point – I just hacked this up quickly to fit my needs.

To get it all working, you need to do four things. The first is, of course, to install this gem.

sudo gem install freelancing-god-ginger --source=

Next, add the following line of code to your spec_helper.rb file (or equivalent):

require 'ginger'

You’ll want to put it as high up as possible – in particular, before any require calls to libraries you want to cover multiple versions of.

Step number three is creating the sets of scenarios in a file called ginger_scenarios.rb, which should go in the root, spec or test directory of your project. Here’s an example, showing off the syntax possibilities.

require 'ginger'

Ginger.configure do |config|
  config.aliases["active_record"] = "activerecord"
  config.scenario('ActiveRecord 1.2.6') do |s|
    s.add /^active_?record$/, '1.15.6'

  config.scenario('ActiveRecord 2.0.2') do |s|
    s.add /^active_?record$/, '2.0.2'

  config.scenario('ActiveRecord 2.1.1') do |s|
    s.add /^active_?record$/, '2.0.2'

Above, I’ve added three different scenarios, for three different versions of ActiveRecord. I also added an alias, as people sometimes use the underscore, and sometimes don’t. The gem’s name has no underscore though, so the value of the alias matches the gem name (whereas the key would be alternative usage).

The older style of defining scenarios is still perfectly valid.

Ginger.configure do |config|
  config.aliases["active_record"] = "activerecord"
  ar_1_2_6 =
  ar_1_2_6[/^active_?record$/] = "1.15.6"
  ar_2_0_2 =
  ar_2_0_2[/^active_?record$/] = "2.0.2"
  ar_2_1_1 =
  ar_2_1_1[/^active_?record$/] = "2.1.1"
  config.scenarios << ar_1_2_6 << ar_2_0_2 << ar_2_1_1

You can have multiple gems set in each scenario – and you don’t have to use regular expressions, you can just use straight strings.

config.scenario('Thinking Sphinx 0.9.8') do |s|
  s.add "riddle", "0.9.8"
  s.add "thinking_sphinx", "0.9.8"

Passing a name to the scenario block is optional, but aids readibility when there are many scenarios as it is output above the tests or specs being executed.

And finally, you’ll want to run the tests or specs for each scenario. This is done using the ginger CLI tool, which parrots whatever parameters you give it onto rake. So just do something like:

ginger spec
ginger test
ginger spec:unit