Add flag for specs that should be skipped if currently not connected to the internet

spec/driver_spec.rb

@@ -2568,7 +2568,7 @@ CACHE MANIFEST
     end
   end
 
-  describe "url blacklisting" do
+  describe "url blacklisting", skip_if_offline: true do
     let(:driver) do
       driver_for_app do
         get "/" do
@@ -2651,7 +2651,7 @@ CACHE MANIFEST
     end
   end
 
-  describe "url whitelisting" do
+  describe "url whitelisting", skip_if_offline: true do
     it_behaves_like "output writer" do
       let(:driver) do
         driver_for_html(<<-HTML, browser)

spec/spec_helper.rb

@@ -23,12 +23,24 @@ Capybara.register_driver :reusable_webkit do |app|
   Capybara::Webkit::Driver.new(app, :browser => $webkit_browser)
 end
 
+def has_internet?
+  require 'resolv'
+  dns_resolver = Resolv::DNS.new
+  begin
+    dns_resolver.getaddress("example.com")
+    true
+  rescue Resolv::ResolvError => e
+    false
+  end
+end
+
 RSpec.configure do |c|
   Capybara::SpecHelper.configure(c)
 
   c.filter_run_excluding :skip_on_windows => !(RbConfig::CONFIG['host_os'] =~ /mingw32/).nil?
   c.filter_run_excluding :skip_on_jruby => !defined?(::JRUBY_VERSION).nil?
   c.filter_run_excluding :selenium_compatibility => (Capybara::VERSION =~ /^2\.4\./).nil?
+  c.filter_run_excluding :skip_if_offline => !has_internet?
 
   # We can't support outerWidth and outerHeight without a visible window.
   # We focus the next window instead of failing when closing windows.