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Sunday, November 21, 2010

Error When installing Nokogiri gem - 'no such file to load -- mkmf (LoadError)'

So basically when I try to install nokogiri gem using 'gem install nokogiri', I get the following error:

root@ubuntu:/home# gem install nokogiri
Building native extensions. This could take a while...
ERROR: Error installing nokogiri:
ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb
`require': no such file to load -- mkmf (LoadError)
from extconf.rb:5

Gem files will remain installed in
gems/nokogiri for inspection.
Results logged to

I was able to successfully install nokogiri on Windows and Mac so I was confused as to why it is failing in Ubuntu. I found out that you need to install the ruby1.8-dev to make it work.

sudo apt-get install ruby1.8-dev

If that still does not work try to install the following as well:

sudo apt-get install libxml2 libxml2-dev libxslt1-dev
sudo gem install nokogiri

Then just run the gem install nokogiri:

root@ubuntu:/home# gem install nokogiri -v
Building native extensions. This could take a while...
Successfully installed nokogiri-
1 gem installed
Installing ri documentation for nokogiri-
No definition for parse_memory

No definition for parse_file

No definition for parse_with

No definition for get_options

No definition for set_options
Installing RDoc documentation for nokogiri-

No definition for parse_memory

No definition for parse_file

No definition for parse_with

No definition for get_options

This above solution will also work if you get the following error message:

Could not open library 'xml2' : xml2:
cannot open shared object file: No such file or directory.
Could not open library '' : cannot open shared object file: No such file or directory (LoadError)

as mentioned on this blog

Saturday, November 13, 2010

Installing Gem Bundler in Ubuntu 10/Mac 10.6

Bundler is a ruby gem to manage your application dependencies. Previously I have to install all of my required gems one by one. This is very tedious and error prone when you have alot of gems to install. Also, with bundler you can install the gems into your local project directory so that your project will not use the system gem which might have a different version than what your project uses.

You would need to install ruby in Ubuntu 10

sudo apt-get install build-essential
sudo apt-get install ruby rdoc libopenssl-ruby

The next step is to install the gem bundler. Gem bundler requires us to install RubyGems version > 1.3.6 and this is where I have problem installing it in Ubuntu 10.04

I encounter a few issue in installing gem bundler in Ubuntu 10.04. Ubuntu asks me to install RubyGems using 'apt-get install Rubygems1.9.1'. Then I run the:

gem install bundler
ERROR: Error installing bundler:
bundler requires RubyGems version >= 1.3.6

And I get the bundler requires RubyGems version error. I found out that I have to install the bundler manually using ruby setup.
This steps have been tested in both Ubuntu and Mac OS X 10.6.6

1. Download the rubygems directly from
2. Unpack the files (tar zxvf rubygems-1.3.7.tgz)
3. cd rubygems-1.3.7
4. ruby setup.rb
5. gem install bundler

root@ubuntu:/home/rubygems-1.3.7# gem install bundler
Successfully installed bundler-1.0.3
1 gem installed

Sunday, November 7, 2010

Upgrading to Capybara 0.4.0

So Capybara 0.4.0 is out now and if you do a 'gem install capybara', you will get Capybara 0.4.0 by default. This has byfar the most changes and not backward compatible with the previous version.

After upgrading to 0.4.0, my test started to fail with a very weird error message ("superclass mismatch for class Node (TypeError)"). It took me one whole day to familiarize myself with the new version which include looking at Capybara code to be able to modify my current test.

Here are what I have to do to upgrade to Capybara 0.4.0 from 0.3.9 in my project

1. Changed "class Node < Capybara::Node" to "class Capybara::Element < Capybara::Node"
See How to send keystrokes to an element in the browser
2. Changed the use of variable "node" to "native"
3. #locate is now deprecated, changed all of my use of "locate" into "find"
4. Changed the way we setup the capybara config


Capybara.default_driver = :selenium
Capybara.run_server = false
Capybara.default_selector = :css
Capybara.default_wait_time = 30


Capybara.configure do |config|
config.default_driver = :selenium
config.default_driver = :selenium
config.run_server = false
config.default_selector = :css
config.default_wait_time = 30

5. Changed the way we register the browser driver


class Capybara::Driver::Selenium
def self.driver
unless @driver

profile =
profile["network.proxy.type"] = 1
profile["network.proxy.http"] = "proxy setting"
profile["network.proxy.http_port"] = 8080
@driver = Selenium::WebDriver.for(:firefox, :profile => profile)

at_exit do


Capybara.register_driver :selenium do |app|
profile =
profile["network.proxy.type"] = 1
profile["network.proxy.http"] = "proxy setting"
profile["network.proxy.http_port"] = 8080, :browser => :firefox, :profile => profile)

Wednesday, November 3, 2010

How to send keystrokes to an element in the browser

From time to time you might need to test sending a keystroke to the browser. For example, for a map based application such as google map, you might want to test the arrow keys on the keyboard to test that pressing the arrow key will move the maps.

Fortunately, webdriver already implements the send-keys class and if you use capybara you can use this extensions by Mark Gandolfo. Please note that as of this writing, the current send-keys version in github does not support capybara 0.4.0 It only supports version < 0.4.0.

However, I have modified the code to work with capybara version 0.4.0 below:

Cucumber Scenario

And I send arrow_left to google map
And I send arrow_up to google map
And I send arrow_right to google map
And I send arrow_down to google map

Steps Definitions - send_keys_steps.rb
put this into your step_definitions directory

And /^I send (.*) to google map$/ do |key|

Class definition - send_keys.rb
put this into your support/patches/send_keys.rb. If you use capybara version < 0.4.0, then change the "Class Capybara::Element < Capybara::Node" into "Node < Capybara::Node" and change the "native.send_keys(send_key)" to "node.send_keys(send_key)".

If you don't, then you will get this error:
"superclass mismatch for class Node (TypeError)"

class Capybara::Driver::Selenium < Capybara::Driver::Base
class Capybara::Element < Capybara::Node
def allowed_keys
@allowed_keys ||= %q(option, null cancel help backspace
tab clear return enter shift left_shift control left_control
alt left_alt pause escape space page_up page_down end home
left arrow_left uparrow_up right arrow_rightdown arrow_down
insert delete semicolon equals numpad0 numpad1 numpad2 numpad3
numpad4 numpad5 numpad6 numpad7 numpad8 numpad9 multiplyadd
separator subtract decimal divide f1 f2 f3 f4 f5 f6 f7 f8
f9 f10 f11 f12)

def send(key)
send_key = []

if key.match(/\[.*\]/i)
key = key.split(',')
key = [key]

key.each do |k|
if k.match(/(\'|\")/i)
send_key << k.gsub(/(\"|\')/, '')
elsif allowed_keys.include?(k)
send_key << k.to_sym
send_key << "#{k}"


Modify support/env.rb to include send_keys

require 'features/support/patches/send_keys'