Testing

Because testing "Journeys" is tedious and repetitive I decided to try some automated testing using Cucumber which I've been using at work.

I opted to use Cucumber with Ruby, interfacing to the browser under test using Selenium. There are good alternatives like Mocha, or Cucumber-js. My choice was based on what I knew and was comfortable with.

The output of the Cucumber tests are here. Warning - or perhaps not a warning. The tests contain the solution of the puzzles in the game.

Installed Xcode and then the command-line tools (which you do from inside Xcode / Preferences / Downloads).

Installed rvm Ruby Version Manager.

Using rvm installed Ruby 1.9.2 using the command rvm install 1.9.2. Set 1.9.2 as the default Ruby by command rvm default 1.9.2.

Installed the Cucumber gem by the command gem install cucumber.

Installed the rspec gem by the command gem install rspec.

Installed the Selenium gem by the command gem install selenium-webdriver.

Here is the start of the feature file as it stood at the time of writing:

Feature: Walkthroughs
	To prove the game works check that solutions work for each
	difficulty level

	Background:
		Given menu page is displayed in browser

	Scenario: No puzzles at all
		When I click on texts "New game" "Calm" "Decks" "122" "122"
		Then I see text "The journey of a thousand miles"

So in the scenario what we want to happen is the browser be started, the menu page for the game displayed, then clicks be simulated on a number of text strings, then we verify we see an expected text.

There is an art to writing good feature steps. A challenge here is not to end up with scenarios which are hundreds of lines long. Compromises have to be made.

So the feature steps have to be wired up using step definitions. For the step:

Given menu page is displayed in browser

The step definition is:

 Given /^menu page is displayed in browser$/ do
open_menu
sleep 5
 end

Where open_menu is a method added to the World.

For the step:

Then I see text "The journey of a thousand miles"

The step definition is:

 Then /^I see text "(.*)"$/ do |text|
find_text( text).should_not be_nil
 end

Having got our step definitions we then need to wire those up to the browser using Selenium. So the method open_menu is implemented as:

 def open_menu
@@driver = Selenium::WebDriver.for :firefox
@@driver.navigate.to "file://localhost" + ENV["MENU"]
mask = @@driver.find_element( :id, 'mask')
@@x_offset = mask.location.x
@@y_offset = mask.location.y
 end

where we pass the file location of the game's index.html page as an environment variable.

We need the x_offset and y_offset data to work out locations relative to the container holding the game elements.

If the Javascript code under test in the browser raises a Javascript alert this hoses Selenium pretty thoroughly. So avoid doing this.

The state of the data inside the browser can be volatile between calls into Selenium from the Ruby code. The test code has to allow for pages needing time to load, or Javascript running during test execution say on a timer. You might get Selenium::WebDriver::Error::StaleElementReferenceError being thrown if the Ruby code has a handle on an element which gets deleted inside the browser.

The tests took a long time to run for a number of reasons. I was walking over the elements in a webpage using Ruby code which meant a lot of Selenium talking to the browser. Faster would be to do this in Javascript with a single Selenium browser interaction. There were delays in the game Javascript code (to prevent duplicate clicks for instance) and these could be minimised when testing.