Add Rake task to fetch ace_modes, and skip test if there's no internet

Rakefile

@@ -3,13 +3,15 @@ require 'rake/clean'
 require 'rake/testtask'
 require 'yaml'
 require 'yajl'
+require 'open-uri'
+require 'json'
 
 task :default => :test
 
 Rake::TestTask.new
 
-# Extend test task to check for samples
-task :test => :check_samples
+# Extend test task to check for samples and fetch latest Ace modes
+task :test => [:check_samples, :fetch_ace_modes]
 
 desc "Check that we have samples.json generated"
 task :check_samples do
@@ -18,6 +20,26 @@ task :check_samples do
   end
 end
 
+desc "Fetch the latest Ace modes from its GitHub repository"
+task :fetch_ace_modes do
+  ACE_FIXTURE_PATH = File.join('test', 'fixtures', 'ace_modes.json')
+
+  File.delete(ACE_FIXTURE_PATH) if File.exist?(ACE_FIXTURE_PATH)
+
+  begin
+    ace_github_modes = (open("https://api.github.com/repos/ajaxorg/ace/contents/lib/ace/mode").read)
+    File.write(ACE_FIXTURE_PATH, ace_github_modes)
+  rescue => e
+    case e
+    when OpenURI::HTTPError
+    when SocketError
+      # no internet? no problem.
+    else
+      raise e
+    end
+  end
+end
+
 task :samples do
   require 'linguist/samples'
   json = Yajl.dump(Linguist::Samples.data, :pretty => true)