文章摘自: https://github.com/watir/watirbook/blob/master/installation/mac.md
Mac OS X 10.9
I> You will need internet access if you want to follow examples. All examples are tested with Mac OS X 10.9. All browsers are English (US) version.
Ruby
Good news is that Ruby is already installed by default. To check Ruby version, open Terminal application any type
ruby -v. If you are not familiar with Terminal, see Command-line interface chapter.
You should get this:
$ ruby -v
ruby 2.0.0p247 (2013-06-27 revision 41674)
[universal.x86_64-darwin13]
RubyGems
It is already installed, but an old version. Let's see which version is here with
gem -v.
You should get this:
$ gem -v
2.0.3
Fortunately, it is easy to upgrade RubyGems with
sudo gem update --system:$ sudo gem update --system
(...)
RubyGems 2.1.11 installed
(...)
selenium-webdriver
Let's try selenium-webdriver gem. Install it with
sudo gem install selenium-webdriver --no-ri --no-rdoc.
You will probably get this:
$ sudo gem install selenium-webdriver
(...)
Fetching: ffi-1.9.3.gem (100%)
Building native extensions. This could take a
while...
ERROR: Error installing selenium-webdriver:
ERROR: Failed to build gem native extension.
(...)
Fortunately, it is easy to fix. Install command line developer tools. To install them, type this into Terminal.
$ git --version
A popup will appear asking if you would like to install command line developer tools.
Click Install. After the installation is finished, try again:
$ sudo gem install selenium-webdriver --no-ri
--no-rdoc
(...)
Successfully installed selenium-webdriver-2.37.0
(...)
