Selenium chromedriver not playing nice with at_exit

Question

Is this a bug in my code, or a bug in Selenium, RSpec, etc.?

The Cucumber tests I'm writing need to shut down and re-launch the Chrome driver. However, I can't get this second driver to shut down properly. The stripped-down example below shows the problem: (The code below is RSpec only because it demonstrates the issue without adding the complexity of Cucumber.)

require 'selenium-webdriver'

RSpec.configure do |config|
       config.before(:suite) do
           $driver = Selenium::WebDriver.for :chrome
         end
     end

describe "A potential rspec/selenium/chrome driver bug" do 
  it "doesn't play nice with at_exit" do    
    # quit the initial driver and start a new one.
    $driver.quit
    $driver = Selenium::WebDriver.for :chrome    
  end # it
end # end describe

at_exit do
  $driver.quit
end

When I run this code I get the following error:

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/net/http.rb:878:in `initialize': Connection refused - connect(2) (Errno::ECONNREFUSED)
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/net/http.rb:878:in `open'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/net/http.rb:878:in `block in connect'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/timeout.rb:52:in `timeout'

I can tell that the second chromedriver process no longer running when the at_exit block runs. This causes a problem because whatever mechanism is causing the shutdown is leaving the Chrome window open.

RSpec's after(:suite) mechanism works as expected. Is there a corresponding mechanism for Cucumber (other than at_exit, which isn't working in this case)? Or, is there a way to prevent chomedriver from exiting before the at_exit block runs (so I can shut it down using the quit method as expected)?

I'm running Ruby 2.0.0 on Mac OS 10.9.5 using the latest selenium and rspec packages.

The code runs as expected with the Safari and Firefox drivers. I get the same error running this code with the Chrome driver in CentOS Linux. — Zack, Jul 06 '15 at 14:18

score 2 · Accepted Answer · answered Jul 07 '15 at 19:35

The problem is a bug in my code. The driver needs to be created before env.rb defines its own at_exit hook. Here's why:

A typical env.rb for cucumber looks like this:

$driver = Selenium::WebDriver.for :chrome, :switches => %w[--disable-cache --ignore-certificate-errors]

at_exit do
  $driver.quit
end

The code that creates the driver object (Selenium::WebDriver.for :chrome) also registers an at_exit hook that shuts down the chromedriver process.

at_exit hooks run in the opposite order they were created. Therefore, a typical execution of cucumber looks like this:

env.rb creates a new driver
Driver defines at_exit hook to quit itself
env.rb defines at_exit hook to quit driver
Cucumber features run
at_exit hook from env.rb is called
Driver's at_exit hook is called

In my case, I created a driver inside a cucumber feature, which caused the driver's at_exit hook to be defined after the at_exit hook in env.rb. As a result, the driver's at_exit hook runs first, causing the call to $driver.quit in env.rb to fail.

The best solution in this case is to create a second driver when necessary and destroy that second driver at the end of the scenario (as opposed to replacing the primary driver with a new one).

Thanks to Alex Rodionov for pointing out my mistakes. https://github.com/SeleniumHQ/selenium/issues/742

Selenium chromedriver not playing nice with at_exit

1 Answers1