Add custom matcher css method like xpath.

README.rdoc

@@ -621,12 +621,17 @@ find yourself using the same kinds of selectors very often:
       xpath { |num| ".//tbody/tr[#{num}]" }
     end
 
+    Capybara.add_selector(:flash_type) do
+      css { |type| "#flash.#{type}" }
+    end
+
 The block given to xpath must always return an XPath expression as a String, or
 an XPath expression generated through the XPath gem. You can now use these
 selectors like this:
 
     find(:id, 'post_123')
     find(:row, 3)
+    find(:flash_type, :notice)
 
 You can specify an optional match option which will automatically use the
 selector if it matches the argument:

lib/capybara/selector.rb

@@ -55,6 +55,14 @@ def xpath(&block)
       @xpath
     end
 
+    # Same as xpath, but wrap in XPath.css().
+    def css(&block)
+      if block
+        @xpath = xpath { |*args| XPath.css(block.call(*args)) }
+      end
+      @xpath
+    end
+
     def match(&block)
       @match = block if block
       @match

spec/basic_node_spec.rb

@@ -19,6 +19,10 @@
               <option selected="selected">Capybara</option>
             </select>
           </div>
+
+          <section>
+            <div class="subsection"></div>
+          </div>
         </div>
       STRING
     end
@@ -38,6 +42,14 @@
       string.should_not have_selector(:lifeform, "Gorilla")
     end
 
+    it 'allows custom matcher using css' do
+      Capybara.add_selector :section do
+        css { |css_class| "section .#{css_class}" }
+      end
+      string.should     have_selector(:section, 'subsection')
+      string.should_not have_selector(:section, 'section_8')
+    end
+
     it "allows using matchers with text option" do
       string.should have_css('h1', :text => 'Awesome')
       string.should_not have_css('h1', :text => 'Not so awesome')