RSpec matchers use Capybara's selectors' error messages

lib/capybara/rspec_matchers.rb

@@ -13,7 +13,11 @@ module Capybara
         end
 
         failure_message_for_should do |actual|
-          "expected #{normalized[:selector].name} #{normalized[:locator].inspect} to return something from:\n#{actual.inspect}"
+          if normalized[:selector].failure_message
+            normalized[:selector].failure_message.call(wrap(actual))
+          else
+            "expected #{normalized[:selector].name} #{normalized[:locator].inspect} to return something from:\n#{actual.inspect}"
+          end
         end
 
         failure_message_for_should_not do |actual|

spec/rspec_matchers_spec.rb

@@ -136,6 +136,16 @@ describe Capybara::RSpecMatchers do
             "<h1>Text</h1>".should have_selector('//h2')
           end.to raise_error(%r(expected xpath "//h2" to return something))
         end
+
+        it "fails with the selector's failure_message if set" 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
+          expect do
+            '<h1 id="monkey_paul">Monkey John</h1>'.should have_selector(:monkey, 14)
+          end.to raise_error("Monkey John")
+        end
       end
 
       context "with should_not" do
@@ -166,6 +176,16 @@ describe Capybara::RSpecMatchers do
             page.should have_selector("//h1[@id='doesnotexist']")
           end.to raise_error(%r(expected xpath "//h1\[@id='doesnotexist'\]" to return something))
         end
+
+        it "fails with the selector's failure_message if set" 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
+          expect do
+            page.should have_selector(:monkey, 14)
+          end.to raise_error("Monkey John, Monkey Paul")
+        end
       end
 
       context "with should_not" do