Specify failure message for selectors

lib/capybara/node/finders.rb

@@ -29,8 +29,11 @@ module Capybara
         rescue TimeoutError
         end
         unless node
-          options = if args.last.is_a?(Hash) then args.last else {} end
-          raise Capybara::ElementNotFound, options[:message] || "Unable to find '#{args[1] || args[0]}'"
+          options = extract_normalized_options(args)
+          normalized = Capybara::Selector.normalize(*args)
+          message = options[:message] || "Unable to find #{normalized[:selector].name} #{normalized[:locator].inspect}"
+          message = normalized[:selector].failure_message.call(self) if normalized[:selector].failure_message
+          raise Capybara::ElementNotFound, message
         end
         return node
       end
@@ -117,7 +120,7 @@ module Capybara
       def all(*args)
         options = extract_normalized_options(args)
 
-        Capybara::Selector.normalize(*args).
+        Capybara::Selector.normalize(*args)[:xpaths].
           map    { |path| find_in_base(path) }.flatten.
           select { |node| matches_options(node, options) }.
           map    { |node| convert_element(node) }
@@ -139,7 +142,7 @@ module Capybara
       def first(*args)
         options = extract_normalized_options(args)
 
-        Capybara::Selector.normalize(*args).each do |path|
+        Capybara::Selector.normalize(*args)[:xpaths].each do |path|
           find_in_base(path).each do |node|
             if matches_options(node, options)
               return convert_element(node)

lib/capybara/selector.rb

@@ -16,18 +16,24 @@ module Capybara
       end
 
       def normalize(name_or_locator, locator=nil)
-        xpath = if locator
-          all[name_or_locator.to_sym].call(locator)
+        result = {}
+
+        if locator
+          result[:selector] = all[name_or_locator]
+          result[:locator] = locator
         else
-          selector = all.values.find { |s| s.match?(name_or_locator) }
-          selector ||= all[Capybara.default_selector]
-          selector.call(name_or_locator)
+          result[:selector] = all.values.find { |s| s.match?(name_or_locator) }
+          result[:locator] = name_or_locator
         end
+        result[:selector] ||= all[Capybara.default_selector]
+
+        xpath = result[:selector].call(result[:locator])
         if xpath.respond_to?(:to_xpaths)
-          xpath.to_xpaths
+          result[:xpaths] = xpath.to_xpaths
         else
-          [xpath.to_s].flatten
+          result[:xpaths] = [xpath.to_s].flatten
         end
+        result
       end
     end
 
@@ -46,6 +52,11 @@ module Capybara
       @match
     end
 
+    def failure_message(&block)
+      @failure_message = block if block
+      @failure_message
+    end
+
     def call(locator)
       @xpath.call(locator)
     end

lib/capybara/spec/session/find_spec.rb

@@ -79,6 +79,18 @@ shared_examples_for "find" do
       end
     end
 
+    context "with custom selector with failure_message option", :focus => true do
+      it "it should raise an error with the failure message if the element is not found" do
+        Capybara.add_selector(:monkey) do
+          xpath { |num| ".//*[contains(@id, 'monkey')][#{num}]" }
+          failure_message { |node| node.all(".//*[contains(@id, 'monkey')]").map { |node| node.text }.sort.join(', ') }
+        end
+        running do
+          @session.find(:monkey, '14').text.should == 'Monkey Paul'
+        end.should raise_error(Capybara::ElementNotFound, "Monkey John, Monkey Paul")
+      end
+    end
+
     context "with css as default selector" do
       before { Capybara.default_selector = :css }
       it "should find the first element using the given locator" do
@@ -97,7 +109,7 @@ shared_examples_for "find" do
     it "should raise ElementNotFound with a useful default message if nothing was found" do
       running do
         @session.find(:xpath, '//div[@id="nosuchthing"]').should be_nil
-      end.should raise_error(Capybara::ElementNotFound, "Unable to find '//div[@id=\"nosuchthing\"]'")
+      end.should raise_error(Capybara::ElementNotFound, "Unable to find xpath \"//div[@id=\\\"nosuchthing\\\"]\"")
     end
 
     it "should accept an XPath instance and respect the order of paths" do