Add documentation for system tests

* Document Rails::SystemTestCase
* Document setting drivers with the configration options
* Document using the getter/setter for driver adapters
* Document the CapybaraRackTestDriver and defaults
* Document the CapybaraSeleniumDriver and defaults
* Document custom assertions provided by System Testing
* Document custom form helpers provided by System Testing

1 files changed, 10 insertions, 1 deletions

diff --git a/actionpack/lib/system_testing/driver_adapter.rb b/actionpack/lib/system_testing/driver_adapter.rb
index 47d37a26b7..cf44a4fd6b 100644
--- a/actionpack/lib/system_testing/driver_adapter.rb
+++ b/actionpack/lib/system_testing/driver_adapter.rb
@@ -1,18 +1,27 @@
 require 'system_testing/driver_adapters'
 
 module SystemTesting
+  # The <tt>SystemTesting::DriverAdapter</tt> module is used to load the driver
+  # set in your Rails' test configuration file.
+  #
+  # The default driver adapters is the +:capybara_rack_test_driver+.
   module DriverAdapter
     extend ActiveSupport::Concern
 
     module ClassMethods
-      def default_driver
+      def default_driver # :nodoc
         :capybara_rack_test_driver
       end
 
+      # Returns the current driver that is set. If no driver is set in the
+      # Rails' configuration file then +:capybara_rack_test_driver+ will be
+      # initialized.
       def driver
         @driver ||= DriverAdapters.lookup(default_driver).new
       end
 
+      # Specify the adapter and settings for the system test driver set in the
+      # Rails' configuration file.
       def driver=(adapter)
         @driver = case adapter
         when Symbol