Test if convert binary is available.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@10014 e93f8b46-1217-0410-a6f0-8f06a7374b81

test/test_helper.rb

@@ -129,10 +129,7 @@ class ActiveSupport::TestCase
   end
 
   def self.convert_installed?
-    bin = Redmine::Configuration['imagemagick_convert_command'] || 'convert'
-    system("#{bin} -version")
-  rescue
-    false
+    Redmine::Thumbnail.convert_available?
   end
 
   # Returns the path to the test +vendor+ repository