Add default_selector into session as well in case DSL isn't being used. Add some specs.

lib/capybara/dsl.rb

@@ -1,7 +1,7 @@
 module Capybara
   class << self
     attr_writer :default_driver, :current_driver, :javascript_driver
-    attr_writer :default_selector
+    attr_reader :default_selector
 
     attr_accessor :app
 
@@ -23,15 +23,24 @@ module Capybara
     end
 
     def current_session
-      session_pool["#{current_driver}#{app.object_id}"] ||= Capybara::Session.new(current_driver, app)
+      session_pool["#{current_driver}#{app.object_id}"] ||= begin
+        session = Capybara::Session.new(current_driver, app)
+        session.default_selector = default_selector if default_selector
+        session
+      end
+    end
+    
+    def current_session?
+      session_pool.has_key?("#{current_driver}#{app.object_id}")
     end
     
     def reset_sessions!
       @session_pool = nil
     end
     
-    def default_selector
-      @default_selector ||= :xpath
+    def default_selector=(selector)
+      @default_selector = selector
+      current_session.default_selector = selector if current_session?
     end
 
   private

lib/capybara/session.rb

@@ -12,6 +12,7 @@ class Capybara::Session
   }
 
   attr_reader :mode, :app
+  attr_writer :default_selector
 
   def initialize(mode, app)
     @mode = mode
@@ -31,6 +32,10 @@ class Capybara::Session
     end
   end
   
+  def default_selector
+    @default_selector ||= :xpath
+  end
+  
   def visit(path)
     driver.visit(path)
   end
@@ -92,7 +97,7 @@ class Capybara::Session
   end
   
   def within(kind, scope=nil)
-    kind, scope = Capybara.default_selector, kind unless scope
+    kind, scope = default_selector, kind unless scope
     scope = css_to_xpath(scope) if kind == :css
     raise Capybara::ElementNotFound, "scope '#{scope}' not found on page" if find(scope).empty?
     scopes.push(scope)

spec/dsl_spec.rb

@@ -11,6 +11,7 @@ describe Capybara do
   after do
     Capybara.default_driver = nil
     Capybara.use_default_driver
+    Capybara.default_selector = nil
   end
 
   describe '#default_driver' do
@@ -108,6 +109,20 @@ describe Capybara do
     end
   end
 
+  describe '#default_selector' do
+    after do
+      Capybara.default_selector = nil
+    end
+    
+    it "should set the selector used in current and future sessions" do
+      Capybara.default_selector.should_not eql(:css)
+      Capybara.default_selector = :css
+      Capybara.current_session.default_selector.should eql(:css)
+      Capybara.reset_sessions!
+      Capybara.current_session.default_selector.should eql(:css)
+    end
+  end
+
   describe 'the DSL' do
     before do
       @session = Capybara

spec/session_spec.rb

@@ -543,6 +543,23 @@ shared_examples_for "session" do
       end
     end
     
+    context "with the default selector" do
+      it "should use XPath" do
+        lambda {
+          @session.within("//li[contains(., 'With Simple HTML')]") { }
+        }.should_not raise_error
+      end
+    end
+    
+    context "with the default selector set to CSS" do
+      it "should use CSS" do
+        @session.default_selector = :css
+        lambda {
+          @session.within("ul li[contains('With Simple HTML')]") { }
+        }.should_not raise_error
+      end
+    end
+    
     context "with click_link" do
       it "should click links in the given scope" do
         @session.within("//li[contains(.,'With Simple HTML')]") do