minor: extra rake tasks for tests. don't show C ext warning when testing

Rakefile

@@ -176,23 +176,40 @@ namespace :gem do
 
   desc "Install the gem locally"
   task :install do
+    sh "gem install --no-rdoc --no-ri json"
+
+    sh "gem uninstall -x -a -I bson"
     sh "gem build bson.gemspec"
-    sh "gem install bson-*.gem"
+    sh "gem install --no-rdoc --no-ri bson-*.gem"
+
+    sh "gem uninstall -x -a -I mongo"
     sh "gem build mongo.gemspec"
-    sh "gem install mongo-*.gem"
+    sh "gem install --no-rdoc --no-ri mongo-*.gem"
+
     sh "rm mongo-*.gem"
     sh "rm bson-*.gem"
   end
 
   desc "Install the optional c extensions"
   task :install_extensions do
+    sh "gem uninstall -x -a -I bson_ext"
     sh "gem build bson_ext.gemspec"
-    sh "gem install bson_ext-*.gem"
+    sh "gem install --no-rdoc --no-ri bson_ext-*.gem"
     sh "rm bson_ext-*.gem"
   end
 
 end
 
+namespace :ci do
+  namespace :test do
+    task :c do
+      Rake::Task['gem:install'].invoke
+      Rake::Task['gem:install_extensions'].invoke
+      Rake::Task['test:c'].invoke
+    end
+  end
+end
+
 task :default => :list
 
 task :list do

lib/bson.rb

@@ -60,12 +60,14 @@ else
     module BSON
       BSON_CODER = BSON_RUBY
     end
+    unless ENV['TEST_MODE']
       warn "\n**Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance."
       warn "  You can install the extension as follows:\n  gem install bson_ext\n"
       warn "  If you continue to receive this message after installing, make sure that the"
       warn "  bson_ext gem is in your load path and that the bson_ext and mongo gems are of the same version.\n"
     end
   end
+end
 
 require 'bson/types/binary'
 require 'bson/types/code'