Implement HTTP::CookieJar#empty? without an argument.

lib/http/cookie_jar.rb

@@ -46,8 +46,15 @@ class HTTP::CookieJar
     }.sort
   end
 
-  def empty?(url)
-    cookies(url).empty?
+  # Tests if the jar is empty.  If url is given, tests if there is no
+  # cookie for the URL.
+  def empty?(url = nil)
+    if url
+      each(url) { return false }
+      return true
+    else
+      @jar.empty?
+    end
   end
 
   # Iterate over cookies.  If +uri+ is given, cookies not for the

test/test_http_cookie_jar.rb

@@ -25,6 +25,15 @@ class TestHTTPCookieJar < Test::Unit::TestCase
    }.merge(options)
   end
 
+  def test_empty?
+    assert_equal true, @jar.empty?
+    cookie = HTTP::Cookie.new(cookie_values)
+    @jar.add(cookie)
+    assert_equal false, @jar.empty?
+    assert_equal false, @jar.empty?('http://rubyforge.org/')
+    assert_equal true, @jar.empty?('http://example.local/')
+  end
+
   def test_two_cookies_same_domain_and_name_different_paths
     url = URI 'http://rubyforge.org/'