Return element and position for ClickFailed error

lib/capybara/webkit/errors.rb

@@ -13,7 +13,7 @@ module Capybara::Webkit
 
   class ClickFailed < StandardError
     def self.json_create(o)
-      new
+      new(o["message"])
     end
   end
 

spec/integration/session_spec.rb

@@ -400,7 +400,7 @@ describe Capybara::Session do
 
       lambda {
         subject.find(:css, '#one').click
-      }.should raise_error(Capybara::Webkit::ClickFailed)
+      }.should raise_error(Capybara::Webkit::ClickFailed, /\[@id='one'\] at position/)
     end
 
     it 'raises an error if a checkbox is obscured when checked' do
@@ -424,7 +424,7 @@ describe Capybara::Session do
     it 'raises an error if an element is not visible when clicked' do
       subject.visit('/')
       subject.execute_script "document.getElementById('foo').style.display = 'none'"
-      lambda { subject.click_link "Click Me" }.should raise_error(Capybara::Webkit::ClickFailed)
+      lambda { subject.click_link "Click Me" }.should raise_error(Capybara::Webkit::ClickFailed, /\[@id='foo'\] at unknown/)
     end
 
     it 'raises an error if an element is not in the viewport when clicked' do

src/capybara.js

@@ -136,7 +136,7 @@ Capybara = {
     if (pos && this.clickTest(node, pos))
       CapybaraInvocation.click(pos.absoluteX, pos.absoluteY);
     else
-      throw new Capybara.ClickFailed();
+      throw new Capybara.ClickFailed(this.path(index), pos);
   },
 
   trigger: function (index, eventName) {
@@ -359,8 +359,13 @@ Capybara = {
   }
 };
 
-Capybara.ClickFailed = function() {
+Capybara.ClickFailed = function(path, position) {
   this.name = 'Capybara.ClickFailed';
+  this.message = 'Failed to click element ' + path;
+  if (position)
+    this.message += ' at position ' + position["absoluteX"] + ', ' + position["absoluteY"];
+  else
+    this.message += ' at unknown position';
 };
 Capybara.ClickFailed.prototype = new Error();
 Capybara.ClickFailed.prototype.constructor = Capybara.ClickFailed;